High resolution organic light-emitting diode devices, displays, and related methods

ABSTRACT

A method of manufacturing an organic-light emitting diode (OLED) display can include providing on a substrate a first electrode associated with a first sub-pixel and a second electrode associated with a second sub-pixel, wherein a gap is formed between the first electrode and the second electrode and wherein the first electrode and the second electrode are positioned in a well having boundaries defined by a confinement structure on the substrate. The method can also include depositing in the well with the electrodes positioned therein, active OLED material to form a substantially continuous layer of active OLED material that spans the boundaries of the well such that a surface of the layer of active OLED material that faces away from the substrate has a non-planar topography. The depositing can be via inkjet printing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation case of U.S. patent application Ser.No. 15/406,455, filed Jan. 13, 2017. U.S. Ser. No. 15/406,455 is acontinuation case of U.S. patent application Ser. No. 14/030,776, filedSep. 18, 2013. U.S. Ser. No. 14/030,776 claims the benefit U.S.Provisional Patent Application No. 61/753,692, filed Jan. 17, 2013,which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

Aspects of the present disclosure generally relate to electronicdisplays and methods for making electronic displays. More particularly,aspects of the present disclosure relate to depositing organiclight-emissive layers on a substrate so as to fabricate high resolutiondisplays.

INTRODUCTION

The section headings used herein are for organizational purposes onlyand are not to be construed as limiting the subject matter described inany way.

Electronic displays are present in many differing kinds of electronicequipment such as, for example, television screens, computer monitors,cell phones, smart phones, tablets, handheld game consoles, etc. Onetype of electronic display relies on organic light emitting diode (OLED)technology. OLED technology utilizes an organic light-emissive layersandwiched between two electrodes disposed on a substrate. A voltage canbe applied across the electrodes causing charge carriers to be excitedand injected into the organic light-emissive layer. Light emission canoccur through photoemission as the charge carriers relax back to normalenergy states. OLED technology can provide displays with a relativelyhigh contrast ratio because each pixel can be individually addressed toproduce light emission only within the addressed pixel. OLED displaysalso can offer a wide viewing angle due to the emissive nature of thepixels. Power efficiency of an OLED display can be improved over otherdisplay technologies because an OLED pixel only consumes power whendirectly driven. Additionally, the panels that are produced can be muchthinner than in other display technologies due to the light-generatingnature of the technology eliminating the need for light sources withinthe display itself and the thin device structure. OLED displays also canbe fabricated to be flexible and bendable due to the compliant nature ofthe active OLED layers.

Inkjet printing is a technique that can be utilized in OLEDmanufacturing, and may reduce manufacturing cost. Inkjet printing usesdroplets of ink containing OLED layer material and one or more carrierliquids ejected from a nozzle at a high speed to produce one or moreactive OLED layers including, for example a hole injection layer, a holetransport layer, an electron blocking layer, an organic light emissivelayer, an electron transport layer, an electron injecting layer, and ahole blocking layer.

To form sub-pixels and prevent OLED ink from spreading between definedsub-pixels, confinement structures such as banks are provided on thesubstrate to define confinement wells. Inkjet printing methods canrequire substantial precision. In particular, as pixel densityincreases, the confinement areas of the confinement wells are reducedand small errors in droplet placement can cause the droplet to bedeposited outside the intended well. Moreover, droplet volumes can betoo large with respect to the confinement well and droplets canundesirably spill over into adjacent sub-pixels. In addition,non-uniformities can form at the edges of the confinement wells due tofilm drying imperfections. As the confinement well area is reduced, thenon-uniformities can encroach on the active emission area of the pixelcreating undesirable visual artifacts in the light emission from thepixel caused by the non-uniformities. In addition, the ratio of theactive area to the total area, both the active and non-active areas, ofeach pixel (referred to as the “fill factor”) is reduced due to theconfinement structures which in turn can reduce the lifetime of thedisplay because each pixel has to be driven using more current toachieve equivalent display brightness levels and using more current todrive each pixel is known to reduce the pixel lifetime.

Although traditional inkjet methods address some of the challengesassociated with OLED manufacturing, there exists a continued need forimprovement. For example, there exists a continued need to reduce thesensitivity of the OLED manufacturing process to the droplet placementprecision, in particular for OLED displays having a high resolution(i.e., high pixel density). Moreover, there exists a need to reduceundesirable visual artifacts created by the deposition of the organiclight-emissive layer in high resolution displays. There also exists aneed to improve the device lifetime by improving the fill factor of eachpixel such that the area associated with active elements is increased.Further, there exists a need for improvement in using and manufacturingOLED displays in high resolution display applications, including but notlimited to, for example, high resolution mobile phones and tabletcomputers, which present challenges in achieving acceptable resolution,power efficiency, display lifetime, and manufacturing cost.

SUMMARY

The present disclosure may solve one or more of the above-mentionedproblems and/or achieve one or more of the above-mentioned desirablefeatures. Other features and/or advantages may become apparent from thedescription which follows.

In accordance with an exemplary embodiment of the present disclosure, amethod of manufacturing an organic-light emitting diode (OLED) displaycan include providing on a substrate a first electrode associated with afirst sub-pixel and a second electrode associated with a secondsub-pixel, wherein a gap is formed between the first electrode and thesecond electrode and wherein the first electrode and the secondelectrode are positioned in a well having boundaries defined by aconfinement structure on the substrate. The method can also includedepositing in the well with the electrodes positioned therein, activeOLED material to form a substantially continuous layer of active OLEDmaterial that spans the boundaries of the well such that a surface ofthe layer of active OLED material that faces away from the substrate hasa non-planar topography. The depositing can be via inkjet printing. Thepresent disclosure also contemplates an organic light emitting diode(OLED) display made according to the above method.

In accordance with an additional exemplary embodiment of the presentdisclosure, an organic light-emitting diode (OLED) display can include afirst electrode disposed on a substrate, wherein the first electrode isassociated with a first sub-pixel; and a second electrode disposed onthe substrate and spaced from the first electrode to provide a gapbetween the first and second electrodes, wherein the second electrode isassociated with a second sub-pixel. The display can further include aconfinement structure positioned on the substrate to define boundariesof a well containing the first electrode and the second electrode; and asubstantially continuous active OLED material layer that spans theboundaries of the well and is disposed over the first electrode andsecond electrodes, wherein a surface of the active OLED material layerthat faces away from the substrate has a non-planar topography.

Additional objects and advantages will be set forth in part in thedescription which follows, and in part will be obvious from thedescription, or may be learned by practice of the present teachings. Atleast some of the objects and advantages of the present disclosure maybe realized and attained by means of the elements and combinationsparticularly pointed out in the appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed. It should beunderstood that the invention, in its broadest sense, could be practicedwithout having one or more features of these exemplary aspects andembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate some exemplary embodiments of thepresent disclosure together with the description, serve to explaincertain principles. In the drawings,

FIG. 1 is a partial plan view of a conventional pixel arrangement.

FIG. 2 is a partial plan view of an exemplary pixel arrangement inaccordance with the present disclosure;

FIG. 3A is a cross-sectional view of a confinement well along line 3A-3Ain FIG. 1 of an exemplary embodiment in accordance with the presentdisclosure;

FIG. 3B is a cross-sectional view of a plurality of confinement wellsalong line 3B-3B in FIG. 1 of an exemplary embodiment in accordance withthe present disclosure;

FIG. 4 is a cross-sectional view similar to the view of FIG. 3A ofanother exemplary embodiment of a confinement well in accordance withthe present disclosure;

FIG. 5A is a cross-sectional view similar to the view of FIG. 3A ofanother exemplary embodiment of a confinement well in accordance withthe present disclosure;

FIG. 5B is a cross-sectional view similar to the view of FIG. 3B ofanother embodiment of a confinement well in accordance with the presentdisclosure;

FIG. 6 is a cross-sectional view of yet another exemplary embodiment ofa confinement well in accordance with the present disclosure;

FIG. 7 is a cross-sectional view of yet another exemplary embodiment ofa confinement well in accordance with the present disclosure;

FIGS. 8-11 are cross-sectional views of another exemplary embodiment ofa confinement well and exemplary steps for creating an OLED display inaccordance with the present disclosure;

FIGS. 12-19 are partial plan views of various exemplary pixelarrangements in accordance with the present disclosure;

FIG. 20 is a front view of an exemplary apparatus including anelectronic display in accordance with the present disclosure; and

FIG. 21 is a front view of another exemplary apparatus including anelectronic display in accordance with the present disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference will now be made in detail to various exemplary embodiments ofthe present disclosure, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

For the purposes of this specification and appended claims, unlessotherwise indicated, all numbers expressing quantities, percentages, orproportions, and other numerical values used in the specification andclaims, are to be understood as being modified in all instances by theterm “about,” to the extent they are not already so modified.Accordingly, unless indicated to the contrary, the numerical parametersset forth in the following specification and attached claims areapproximations that may vary depending upon the desired propertiessought to be obtained. At the very least, and not as an attempt to limitthe application of the doctrine of equivalents to the scope of theclaims, each numerical parameter should at least be construed in lightof the number of reported significant digits and by applying ordinaryrounding techniques.

It is noted that, as used in this specification and the appended claims,the singular forms “a,” “an,” and “the,” and any singular use of anyword, include plural referents unless expressly and unequivocallylimited to one referent. As used herein, the term “include” and itsgrammatical variants are intended to be non-limiting, such thatrecitation of items in a list is not to the exclusion of other likeitems that can be substituted or added to the listed items.

Further, this description's terminology is not intended to limit theinvention. For example, spatially relative terms—such as “beneath”,“below”, “lower”, “top”, “bottom”, “above”, “upper”, “horizontal”,“vertical”, and the like—may be used to describe one element's orfeature's relationship to another element or feature as illustrated inthe figures. These spatially relative terms are intended to encompassdiffering positions (i.e., locations) and orientations (i.e., rotationalplacements) of a device in use or operation in addition to the positionand orientation shown in the figures. For example, if a device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be “above” or “over” the other elementsor features. Thus, the exemplary term “below” can encompass bothpositions and orientations of above and below depending on the overallorientation of the device. A device may be otherwise oriented (rotated90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

As used herein, “pixel” is intended to mean the smallest functionallycomplete and repeating unit of a light emitting pixel array. The term“sub-pixel” is intended to mean a portion of a pixel that makes up adiscrete light emitting part of the pixel, but not necessarily all ofthe light emitting parts. For example, in a full color display, a pixelcan include three primary color sub-pixels such as red, green, and blue.In a monochrome display, the terms sub-pixel and pixel are equivalent,and may be used interchangeably.

The term “coupled” when used to refer to electronic components isintended to mean a connection, linking, or association of two or moreelectronic components, circuits, systems, or any combination of: (1) atleast one electronic component, (2) at least one circuit, or (3) atleast one system in such a way that a signal (e.g. current, voltage, oroptical signal) can be transferred from one to another. The connection,linking, or association of two or more electronic components, circuits,or systems can be direct; alternatively intermediary connections,linkings, or associations may be present, and thus coupling does notnecessarily require a physical connection.

One of ordinary skill in the art would generally accept the term “highresolution” to mean a resolution greater than 100 pixels per inch (ppi)where 300 ppi can sometimes be referred to as very high resolution. Oneof ordinary skill in the art would also recognize that pixel densitydoes not directly correlate to the size of the display. Variousexemplary embodiments disclosed herein can be used to achieve highresolution in small and large display sizes. For example, displayshaving a size of about 3 inches to about 11 inches can be implemented ashigh resolution displays. Moreover, displays having larger sizes, suchas television displays up to 55″ and beyond, can also be used withvarious exemplary embodiments described herein to achieve highresolution displays.

As used herein, a layer or structure being “on” a surface includes boththe case where the layer is directly adjacent to and in direct contactwith the surface over which it is formed and the case where there areintervening layers or structures between the layer or structure beingformed over the surface.

Various factors can influence deposition precision of organiclight-emissive layers in OLED display manufacturing techniques suchfactors include for example, display resolution, droplet size, targetdroplet area, droplet placement error, fluid properties (e.g., surfacetension, viscosity, boiling point) associated with the OLED layermaterial (e.g., active OLED materials) inks, which are comprised of acombination of OLED layer material and one or more carrier fluids, andthe velocity at which the droplets are deposited. As display resolutionsincrease, for example greater than 100 ppi, or for example greater than300 ppi, various issues arise in using inkjet printing techniques forOLED display manufacturing. High precision inkjet heads used in theconventional printing techniques can produce droplet sizes ranging fromabout 1 picoliter (pL) to about 50 picoliters (pL), with about 10 pLbeing a relatively common size for high precision inkjet printingapplications. Droplet placement accuracy of a conventional inkjetprinting system is approximately ±10 μm. In various exemplaryembodiments, confinement wells can be provided on the substrate tocompensate for droplet placement errors. A confinement well can be astructure that prevents OLED material from migrating beyond a desiredsub-pixel area. To ensure that a droplet accurately lands at a desiredlocation on a substrate, such as entirely within a confinement well,various exemplary embodiments configure the confinement well to be aswide as the droplet diameter plus twice the droplet placement error ofthe system. For example, the diameter of a 10 pL droplet is about 25 μmand thus the preceding parameters would indicate the use of aconfinement well of at least 45 μm (25 μm+(2*10 μm)) in its smallestdimension. Even for a 1 pL droplet, the droplet diameter is 12 μm, whichindicates a confinement well of at least 32 μm in its smallestdimension.

Various pixel layouts that rely on a confinement well of at least 45 μmin its smallest dimension can be used in OLED displays having aresolution up to 100 ppi. However, in high resolution displays ofgreater than 100 ppi, for example, 10 pL droplets are too large anddroplet placement accuracies too poor to reliably provide for consistentloading of droplets into confinement wells around each sub-pixel. Inaddition, as noted above, for high resolution displays, covering anincreased amount of display area with structures used to defineconfinement wells can negatively impact the fill factor of each pixel,where fill factor is defined as the ratio of the light emitting area ofthe pixel relative to the total pixel area. As fill factor decreases,each pixel must be driven harder to achieve the same overall displaybrightness thereby decreasing longevity and performance of each pixel ofthe display.

To further illustrate some of the above mentioned challenges of workingwith very high resolution displays, FIG. 1 illustrates one conventionalpixel layout 1700. Pixel 1750 can comprise sub-pixels 1720, 1730, 1740arranged in a side-by-side configuration, sub-pixel 1720 beingassociated with light emission in the red spectrum range, sub-pixel 1730being associated with light emission in the green spectrum range, andsub-pixel 1740 being associated with light emission in the blue spectrumrange. Each sub-pixel can be surrounded by confinement structures 1704forming confinement wells directly corresponding to the sub-pixels 1720,1730, 1740. One sub-pixel electrode can be associated with eachconfinement well such that electrode 1726 corresponds to sub-pixel 1720,electrode 1736 corresponds to sub-pixel 1730, and electrode 1746corresponds to sub-pixel 1740. Sub-pixel 1720 can have a width D,sub-pixel 1730 can have a width C, and sub-pixel 1740 can have a widthB, which may be the same or differ from each other. As shown, allsub-pixels can have a length A. In addition, dimensions E, F, and G canindicate the spacing between confinement well openings. Values assignedto dimensions E, F, G can be very large in some instances, e.g., greaterthan 100 μm, particularly in lower resolution displays. However, forhigher resolution displays, it is desirable to minimize these dimensionsin order to maximize the active pixel area and thus maximize the fillfactor. As illustrated in FIG. 1, the active pixel area, indicated bythe shaded regions, is the entire area within each of the sub-pixelconfinement wells.

Various factors can influence dimensions E, F, G, such as, for example,the minimum value for these dimensions can be restricted by theprocessing method. For example, in various illustrative embodimentsdescribed herein E=F=G=12 μm as a minimum dimension. For example, in adisplay having a 326 ppi resolution, the pixel pitch can be equal to 78μm and E=F=G=12 μm. The confinement wells associated with each of thesub-pixels 1720, 1730, 1740 can have a target droplet area of 14 μm×66μm (i.e. dimensions B×A, C×A, and D×A) where 14 μm is significantly lessthan the 45 μm smallest dimension discussed above regarding using inkjetdroplets having a volume of 10 pL. It is also less than the 32 μmdimension discussed above for 1 pL droplets. In addition, the fillfactor of the pixel, defined as the ratio of the active pixel area (i.e.the area associated with light emission), and the total pixel area is46%. In other words, 54% of the pixel area corresponds to confinementstructures 1704. Along the same lines, in a display having a 440 ppiresolution, the pixel pitch, P, can be equal to 58 μm and E=F=G=12 μm.Confinement wells associated with each of the emitting sub-pixels 1720,1730, 1740 can have a target droplet area of, for example, 7 μm×46 μmwhere a dimension of 7 μm is significantly less than the minimumdimensions discussed above for accurate droplet placement of both 10 pLand 1 pL inkjet droplets. In this instance, the fill factor for adisplay having 440 ppi is around 30%.

Deposition techniques in accordance with various exemplary embodimentsdescribed herein can provide improved reliability in loading ofconfinement wells and deposition of active OLED layers for electronicdisplays, such as, for example, high resolution displays. Active OLEDlayers can include, for example, one or more of the following layers: ahole injection layer, a hole transport layer, an electron blockinglayer, an organic light emissive layer, an electron transport layer, anelectron injecting layer, and a hole blocking layer. Implementation ofsome of the above-identified active OLED layers is preferred andimplementation of some active OLED layers is optional for electronicdisplays. For example, at least one hole conducting layer such as a holeinjection layer or a hole transport layer must be present as well as anorganic light emissive layer. All other above-identified layers may beincluded as desired to alter (e.g., improve) light emission and powerefficiency of an electronic display such as an OLED display.

Various exemplary embodiments of confinement well configurationsdescribed herein can increase the size of the confinement well whilemaintaining high pixel resolution. For instance, various exemplaryembodiments use relatively large confinement wells that span a pluralityof sub-pixels, thereby enabling the use of relatively attainable dropletsizes and conventional printing system accuracies in the deposition ofthe active OLED layers, while also achieving relatively high pixeldensities. Accordingly, inkjet nozzles that deposit droplet volumes inthe range from 1 pL to 50 pL can be used, rather than requiringspecially configured or reconfigured printheads with smaller dropletvolumes and new printing systems, which may or may not be available.Moreover, by using such larger confinement wells, small manufacturingerrors will not have a significant negative effect on depositionprecision and the deposited active OLED layers can remain containedwithin the confinement well.

In accordance with various exemplary embodiments, inkjet printingtechniques can provide sufficiently uniform deposition of active OLEDlayers. For example, various components typically used in OLED displaysresult in topographies of varying heights on the top surface layer of aconfinement well, for example, heights differing by about 100 nanometers(nm) or more. For instance, components such as electrodes may bedeposited on a substrate such that a gap is formed between neighboringelectrodes in order to form separately addressable electrodes eachassociated with a differing sub-pixel. Regardless of which active OLEDlayers are deposited over the electrodes disposed on the substrate ofthe display, height differentials between the plane of the top surfacesof the electrodes and the top surface of the substrate of the display inregions between neighboring electrodes can contribute to the topographyof the subsequently deposited OLED layers. Exemplary inkjet printingtechniques and resulting displays in accordance with the presentdisclosure allow the active OLED layers to be deposited such that thethickness of the active OLED layers are sufficiently uniform, forexample over the active electrode region, where active electrode regionscan be regions of the electrode associated with the active sub-pixelarea from which light is emitted. In an exemplary embodiment, athickness of the OLED layer, at least over the active electrode region,can be less than the thickness of the sub-pixel electrodes. Sufficientlyuniform thicknesses of the OLED layers over the active electrode areacan reduce undesirable visual artifacts. For example, OLED inkformulations and printing processes can be implemented to minimizenon-uniformity in the deposited film thickness within a given depositionarea, even when that area includes both electrode and non-electroderegions. In other words, portions within the deposition area not coveredby an electrode structure can contribute to the OLED layer topographysuch that the OLED layer can sufficiently conform to the underlyingstructures over which it is deposited within the deposition area.Minimizing non-uniformities in the deposited film thickness can providefor substantially uniform light emission when a particular sub-pixelelectrode is addressed and activated.

In accordance with yet other exemplary embodiments, pixel layoutconfigurations contemplated by the present disclosure can increaseactive region areas. For example, confinement structures can defineconfinement wells having a contiguous area that spans a plurality ofsub-pixels such that non-active portions (e.g., substrate areasassociated with confinement structures) of the display are reduced. Forinstance, rather than a confinement structure surrounding each sub-pixelelectrode as in various conventional OLED displays, a plurality ofindividually addressed sub-pixel electrodes can be surrounded by aconfinement structure where each sub-pixel electrode can be associatedwith a differing pixel. By reducing the area taken up by the confinementstructures, the fill factor can be maximized because the ratio of thenon-active region to the active region of each pixel is increased.Achieving such increases in fill factor can enable high resolution insmaller size displays, as well as improve the lifetime of the display.

In accordance with yet other exemplary embodiments, the presentdisclosure contemplates an organic light-emissive display that includesa confinement structure disposed on a substrate, wherein the confinementstructure defines a plurality of wells in an array configuration. Thedisplay further includes a plurality of electrodes disposed within eachwell and spaced apart from one another. The display further can includefirst, second, and third organic light emissive layers in at least oneof the plurality of wells, each layer having first, second, and thirdlight emissive wavelength ranges, respectively. A number of electrodesdisposed within the well associated with the first and second organiclight-emissive layer differs from a number of electrodes disposed withinthe well associated with the third organic light emissive layer.

In accordance with yet other exemplary embodiments, the presentdisclosure contemplates an organic light-emissive display that includesa confinement structure disposed on a substrate, wherein the confinementstructure defines a plurality of wells in an array configuration,including a first well, a second well, and a third well. The displayfurther can include a first plurality of electrodes disposed within thefirst well and associated with a differing pixel, a second plurality ofelectrodes disposed within the second well and associated with adiffering pixel, and at least one third electrode disposed within thethird well, wherein a number of electrodes disposed within each of thefirst and second wells differs from a number of electrodes disposedwithin the third well. The display can further include a first organiclight emissive layer having a first light-emissive wavelength rangedisposed in the first well, a second organic light emissive layer havinga second light-emissive wavelength range disposed in the second well,and third organic light emissive layer having a third light-emissivewavelength range disposed in the third well.

In accordance with various other exemplary embodiments, pixel layoutconfigurations can be arranged to extend the lifetime of the device. Forexample, sub-pixel electrode size can be based on the correspondingorganic light-emission layer wavelength range. For instance, a sub-pixelelectrode associated with light emission in the blue wavelength rangecan be larger than a sub-pixel electrode associated with light emissionin the red or green wavelength ranges, respectively. Organic layersassociated with blue light emission in OLED devices typically haveshortened lifetimes relative to organic layers associated with red orgreen light emission. In addition, operating OLED devices to achieve areduced brightness level increases the lifetime of the devices. Byincreasing the emission area of the blue sub-pixel relative to the redand green sub-pixels, respectively, in addition to driving the bluesub-pixel to achieve a relative brightness less than a brightness of thered and green sub-pixels (e.g., by adjusting the current supplied whenaddressing the sub-pixel as those of ordinary skill in the art arefamiliar with), the blue sub-pixel can serve to better balance thelifetimes of the differing colored sub-pixels while still providing forthe proper overall color balance of the display. This improved balancingof lifetimes can increase the overall lifetime of the display byextending the lifetime of the blue sub-pixels.

FIG. 2 illustrates a partial, plan view of one exemplary pixelarrangement of an organic light-emitting diode (OLED) display 100according to an exemplary embodiment of the present disclosure. FIG. 3Aillustrates a cross-sectional view along section 3A-3A identified inFIG. 2 of one exemplary embodiment of a substrate, depicting variousstructures for forming an OLED display. FIG. 3B illustrates across-sectional view along section 3B-3B identified in FIG. 2 of oneexemplary embodiment of a substrate, depicting various structures forforming an OLED display.

The OLED display 100 generally includes a plurality of pixels, e.g.,such as defined by dotted line boundaries 150, 151, 152, that whenselectively driven emit light that can create an image to be displayedto a user. In a full color display, a pixel 150, 151, 152 can include aplurality of sub-pixels of differing colors. For example, as illustratedin FIG. 2, pixel 150 can include a red sub-pixel R, a green sub-pixel G,and a blue sub-pixel B. As can be seen in the exemplary embodiment ofFIG. 2, sub-pixels need not be the same size, although in an exemplaryembodiment they could be. Pixels 150, 151, 152 can be defined by drivingcircuitry that cause light emission such that no additional structure isnecessary to define a pixel. Alternatively, exemplary embodiments of thepresent disclosure contemplate various new arrangements of pixeldefinition structures that can be included within display 100 todelineate the plurality of pixels 150, 151, 152. Those having ordinaryskill in the art are familiar with materials and arrangements ofconventional pixel definition structures used to provide crisperdelineation between pixels and sub-pixels.

With reference to FIGS. 3A and 3B in addition to FIG. 2, OLED display100 can include a substrate 102. Substrate 102 can be any rigid orflexible structure that can include one or more layers of one or morematerials. Substrate 102 can include, for example, glass, polymer,metal, ceramic, or combinations thereof. While not illustrated forsimplicity, substrate 102 can include additional electronic components,circuits, or conductive members, with which those having ordinary skillin the art have familiarity. For instance, thin-film transistors (TFTs)(not shown) can be formed on the substrate before depositing any of theother structures that are discussed in further detail below. TFTs caninclude, for example, at least one of a thin film of an activesemiconductor layer, a dielectric layer, and a metallic contact wherethose of ordinary skill in the art would be familiar with materials usedin the manufacture of such TFTs. Any of the active OLED layers can bedeposited to conform to any topography created by TFTs or otherstructures formed on substrate 102, as discussed below.

Confinement structures 104 can be disposed on the substrate 102 suchthat the confinement structures 104 define a plurality of confinementwells. For instance, the confinement structures 104 can be a bankstructure. A plurality of sub-pixels can be associated with eachconfinement well and the organic light-emissive material depositedwithin each confinement well allows all sub-pixels associated with theconfinement well to have the same light emission color. For example, inthe arrangement of FIG. 2, confinement well 120 can receive droplets ofOLED ink associated with sub-pixels that emit red light denoted by R,confinement well 130 can receive droplets of OLED ink associated withsub-pixels that emit green light denoted by G, and confinement well 140can receive droplets of OLED ink associated with sub-pixels that emitblue light denoted by B. Those having ordinary skill in the art wouldappreciate, as will be further explained below, that the confinementwells can also receive various other active OLED layers, including butnot limited to, for example, additional organic light-emissive materialand a hole conducting layer.

The confinement structures 104 can define confinement wells 120, 130,140 to confine material associated with a plurality of sub-pixels. Inaddition, confinement structures 104 can prevent spreading of OLED inkinto adjacent wells, and/or can assist (through appropriate geometry andsurface chemistry) in the loading and drying process such that thedeposited film is continuous within the region bounded by confinementstructures 104. For example, edges of the deposited films can contactthe confinement structures 104 that surround the confinement wells 120,130, 140. The confinement structures 104 can be a single structure orcan be composed of a plurality of separate structures that form theconfinement structures 104.

The confinement structures 104 can be formed of various materials suchas, for example, photoresist materials such as photoimageable polymersor photosensitive silicone dielectrics. The confinement structures 104can comprise one or more organic components that are, after processing,substantially inert to the corrosive action of OLED inks, have lowoutgassing, have a shallow (e.g. <25 degrees) sidewall slope at theconfinement well edge, and/or have high phobicity towards one or more ofthe OLED inks to be deposited into the confinement well, and may bechosen based on the desired application. Examples of suitable materialsinclude, but are not limited to PMMA (poly-methylmethacrylate), PMGI(poly-methylglutarimide), DNQ-Novolacs (combinations of the chemicaldiazonaphithoquinone with different phenol formaldehyde resins), SU-8resists (a line of widely used, proprietary epoxy based resistsmanufactured by MicroChem Corp.), fluorinated variations of conventionalphotoresists and/or any of the aforementioned materials listed herein,and organo-silicone resists, each of which can be further combined witheach other or with one or more additives to further tune the desiredcharacteristics of the confinement structures 104.

Confinement structures 104 can define confinement wells that have anyshape, configuration, or arrangement. For example, the confinement wells120, 130, 140 can have any shape such as rectangular, square, circular,hexagonal, etc. Confinement wells in a single display substrate can havethe same shape and/or size or differing shapes and/or sizes. Confinementwells associated with differing light emission colors can have differingor the same shapes and/or sizes. Moreover, adjacent confinement wellscan be associated with alternating light emission colors or adjacentconfinement wells can be associated with the same light emission colors.In addition, confinement wells can be arranged in columns and/or rowswhere the columns and/or rows can have uniform or non-uniform alignment.

The confinement wells can be formed using any of a variety ofmanufacturing methods, such as, for example, inkjet printing, nozzleprinting, slit coating, spin coating, spray coating, screen printing,vacuum thermal evaporation, sputtering (or other physical vapordeposition method), chemical vapor deposition, etc. and any additionalpatterning not otherwise achieved during the deposition technique can beachieved by using shadow masking, one or more photolithography steps(e.g. photoresist coating, exposure, development, and stripping), wetetching, dry etching, lift-off, etc.

As illustrated in FIG. 2, confinement wells 120, 130, 140 according tovarious exemplary embodiments, can be defined by the confinementstructures 104 such that they span a plurality of pixels 150, 151, 152.For example, pixel 150 includes a red sub-pixel R, a green sub-pixel G,and a blue sub-pixel B that are each part of a differing confinementwell 120, 130, 140. Each confinement well 120, 130, 140 can include aplurality of electrodes, such as 106, 107, 108, 109, 136, 137, 138, 139,142, 144, wherein the electrodes within the confinement wells 120, 130,140 can be spaced apart from each other such that a gap S is formedbetween adjacent electrodes within a confinement well. In exemplaryembodiments, the gap S can be of sufficient size to electrically isolatean electrode from any adjacent electrode, and in particular, the activeelectrode regions of adjacent electrodes can be isolated from oneanother. The gap or space S can reduce current leakage and improvesub-pixel definition and overall pixel definition.

While omitted for clarity and ease of illustration, drive circuitry canbe disposed on the substrate 102, and such circuitry can be disposedeither beneath the active pixel areas (i.e., the light emitting regions)or within the non-active pixel areas (i.e., the non-light emittingregions). In addition, while not illustrated, circuitry can also bedisposed under confinement structures 104. The drive circuitry can becoupled to each electrode such that each electrode can be selectivelyaddressed independently of the other electrodes within the confinementwell. The region of non-uniform topography that results due to the gap Sbetween electrodes is described in further detail below.

Each electrode 106, 107, 108, 109, 136, 137, 138, 139, 142, 144 within aconfinement well 120, 130, 140 can be associated with a differingsub-pixel. For example, as illustrated in FIG. 2, confinement well 120can be associated with red light emission. Electrodes 106, 107, 108, 109can be positioned within the confinement well 120 where each electrodeis operable to address a sub-pixel of a differing pixel (e.g., pixels151 and 152 being illustrated). At least two electrodes can bepositioned within each confinement well 120, 130, 140. The number ofelectrodes positioned within each confinement well 120, 130, 140 can bethe same or differing from other confinement wells. For example, asillustrated in FIG. 2, confinement well 140 can include two sub-pixelelectrodes 142, 144 associated with blue light emission and confinementwell 130 can include four sub-pixel electrodes 136, 137, 138, 139associated with green light emission.

In an exemplary embodiment, the confinement structures 104 can bedisposed on a portion of the electrodes 106, 107, 108, 109, 136, 137,138, 139, 142, 144. As illustrated in FIGS. 3A and 3B, the confinementwell 120 can be defined by the confinement structures 104 where theconfinement structures 104 are disposed partially over a portion ofelectrodes 106, 108 and partially directly over substrate 102 withoutbeing over an electrode. Alternatively, the confinement structures 104can be disposed over the substrate 102 between electrodes of adjacentconfinement wells. For example, the confinement structures 104 can bedisposed on substrate 102 in a space formed between electrodesassociated with a differing sub-pixel emission color such that theconfinement structures 104 are directly disposed on substrate 102 andare not disposed over any portion of an electrode. In such aconfiguration (not illustrated), the electrodes corresponding tosub-pixels can be disposed either directly adjacent to (in abutmentwith) the confinement structures 104 or the electrodes can be spacedapart from the confinement structures 104 such that sub-pixel definitioncan be achieved.

When a voltage is selectively applied to an electrode 106, 107, 108,109, 136, 137, 138, 139, 142, 144, light emission can be generatedwithin a sub-pixel of a pixel, such as, pixels 150, 151, 152. Electrodes106, 107, 108, 109, 136, 137, 138, 139, 142, 144, can be transparent orreflective and can be formed of a conductive material such as a metal, amixed metal, an alloy, a metal oxide, a mixed oxide, or a combinationthereof. For example, in various exemplary embodiments, the electrodesmay be made of indium-tin-oxide, magnesium silver, or aluminum.Electrodes 106, 107, 108, 109, 136, 137, 138, 139, 142, 144, can haveany shape, arrangement, or configuration. For example, referring to FIG.3A, electrodes 106, 107, 108, 109, 136, 137, 138, 139, 142, 144, canhave a profile such that the top surface 106 a, 108 a can besubstantially planar and parallel to the surface of the substrate 102while the side edges 106 b, 108 b of the electrodes can be substantiallyperpendicular to or can be angled and/or rounded with respect to thesurface of the substrate.

It is further noted that the active portion of the electrode, i.e. theportion associated with light emission, are those portions of theelectrode which are disposed directly underneath the deposited OLEDlayers without any intervening insulating substrate structures betweenthe electrode surface and the OLED layers. By way of example, again withreference to FIG. 3A, the portions of electrodes 106 and 108 that aredisposed beneath confinement structures 104 are excluded from the activeportion of the electrode area, whereas the remainder of the regions ofelectrodes 106 and 108 are included in the active portion of theelectrode area.

The electrodes may be deposited in various ways, such as, by a thermalevaporation, chemical vapor deposition, or sputtering method. Thepatterning of the electrodes may be achieved, for example, using shadowmasking or photolithography. As mentioned above, electrodes 106, 107,108, 109, 136, 137, 138, 139, 142, 144 can have a thickness and bespaced apart such that a topography is formed on the substrate 102,shown best in the various cross-sectional views, such as in FIG. 3A. Inan exemplary embodiment, electrodes 106, 107, 108, 109, 136, 137, 138,139, 142, 144 can have a thickness ranging from 60 nm to 120 nm, thoughthis range is nonlimiting and larger or smaller thicknesses are possibleas well.

One or more active OLED layers can be provided within each confinementwell 120, 130, 140 such as hole conducting layer 110 and organic lightemissive layer 112 shown in FIGS. 3A and 3B. The active OLED layers canbe deposited such that they can sufficiently conform to the topographiesthat result from thickness of and spacing between the electrodes 106,107, 108, 109, 136, 137, 138, 139, 142, 144 within a confinement well120, 130, 140, as well as the thickness of the respective active OLEDlayers. For example, the active OLED layers can be continuous within awell and have a thickness so as to sufficiently conform and follow theresultant topography of the underlying electrode structures disposedwithin each confinement well.

The deposited OLED layers may therefore result in a surface topographythat does not lie in a single plane parallel to the substrate and acrossthe entire confinement well. For example, one or both of OLED layers110, 112 can be non-planar and discontinuous in a single plane of thedisplay (wherein the plane of the display is intended as a planeparallel to substrate 102) due to the relative depression or protrusionassociated with any surface feature including electrodes disposed onsubstrate 102. As shown, the OLED layers 110, 112 can sufficientlyconform to underlying surface feature topographies such that a topsurface of the OLED layer can have a resulting topography that followsthe topography of the underlying surface features. In other words, eachdeposited OLED layer sufficiently conforms to all underlying layersand/or surface features disposed on the substrate 102 such that thoseunderlying layers contribute to the resulting non-planar top surfacetopography of the OLED layers after they are deposited. In this way, ina plane across the confinement well that is parallel to a plane of thedisplay, a discontinuity in layer 110 or 112, or both, can arise as thelayer(s) rise and/or fall, relative to the plane, with the existingsurface features provided from electrodes, circuitry, pixel definitionlayers, etc., in the confinement well. While the active OLED layers 110and/or 112 need not perfectly conform to the underlying surfacetopography (for example, as explained below there may be localnon-uniformities in thickness around edge regions and the like), asufficiently conformal coating in which there are no significantbuild-ups or depletions of material can promote a more even, uniform,and repeatable coating.

As shown in FIG. 3A, each layer 110, 112 can be substantially continuouswithin the entire confinement well 120 such that each layer is disposedover substantially all surface features within the confinement well 120(e.g. sub-pixel electrodes, circuitry, pixel definition layers, etc.)where the edges of each layer contact the confinement structures 104surrounding the confinement well 120. In various exemplary embodiments,active OLED layer material can be deposited to form a discretecontinuous layer entirely within a confinement well to substantiallyprevent any discontinuities in the layer within the well (in other wordsa region within the well where the active OLED layer material ismissing). Such discontinuities can cause undesirable visual artifactswithin the emission region of a sub-pixel. It is worth noting thatthough each layer 110, 112 is substantially continuous within theconfinement well, it can nonetheless be discontinuous in a single plane,as noted above, due to the rising/falling of the layer as itsufficiently conforms to existing topographies of features disposed inthe confinement well over which the layers are deposited. For example,in exemplary embodiments, if such a rise and/or fall is by an amount,e.g., 100 nm, greater than the thickness of the thinnest part of thedeposited layer within the well, e.g., 50 nm, the OLED material layerwill not be continuous in a plane parallel to the display within thewell.

The layers 110, 112 can have a substantially uniform thickness withineach confinement well which may provide for more uniform light emission.For the purpose of this application, substantially uniform thickness canrefer to an average thickness of the OLED layer over planar surfaceregions, such as over active electrode regions, but also can encompassminute variations or local non-uniformities in thickness as describedbelow. Over the planar surface regions, e.g. 106 a, 108 a, and bottomsurface of gaps in FIG. 3A, it is anticipated that for a substantiallyuniform OLED coating the variation in thickness from an averagethickness of the OLED layer can be less than ±20%, such as less than±10% or less than ±5%.

As noted above, however it is contemplated that local non-uniformitiesin thickness may arise in portions of the layers 110, 112 surroundingchanges in surface topography and/or surface chemistry, and in suchregions, the film thickness can locally deviate substantially from the±20%, ±10%, or ±5% parameters specified above. For example, localnon-uniformities in the thickness of a continuous layer can occur due tothe topography associated with surface features disposed on substrate102 and/or a change in surface chemistry between the surface featuresdisposed on the substrate 102 such as at the edge of the confinementwell structures 104, at the edge of a pixel definition layer (discussedbelow), on the electrode edge sidewalls (e.g. along 106 b, 108 b), orwhere the electrode meets the substrate surface. Local non-uniformitiescan lead to deviations in film thickness. For example, the localnon-uniformities can deviate from the thickness of the layers 110, 112provided over the active electrode regions (e.g. along 106 a, 108 a) ofelectrodes 106, 108. The non-uniformities can create generally localized“edge effect” deviations within a range of approximately 5 μm-10 μmaround such surface features disposed on substrate 102 in theconfinement well, such as at edges of electrodes, circuitry, pixeldefinition layers, etc. For the purposes of this application, such “edgeeffect” deviations are intended to be encompassed when describing theOLED film coating as having a “substantially uniform thickness” withinthe well.

In an exemplary embodiment, the thickness of each layer 110, 112 can beequal to or less than the thickness of the electrodes such that theupper surface of each layer does not lie in a single plane parallel tothe plane of the display (i.e., a plane parallel to the substrate) dueto the dip in the film formed as the layer traverses the gap between theactive regions of the electrodes. This is illustrated, for example, inFIG. 3A, wherein a dashed line is provided to illustrate a plane P thatis parallel to the plane of the substrate 102. As shown, layers 110, 112can each have an average thickness that is substantially uniform withinthe region of layers 110, 112 over with the active electrode regions ofelectrodes 106, 108. However, layers 110, 112 can also include small andlocalized non-uniform thickness in areas associated with topographychanges caused by the surface features such as around edges of thosesurface features (e.g. edges of electrodes 106, 108 adjacent to thegap).

The layers 110, 112 can be deposited using any manufacturing method. Inan exemplary embodiment, the hole conducting layer 110 and the organiclight-emission layer 112 can be deposited using inkjet printingtechniques. For example, the material of hole conducting layer 110 canbe mixed with a carrier fluid to form an inkjet ink that is formulatedto provide reliable and uniform loading into the confinement wells. Theink for depositing hole conducting layer 110 can be delivered to thesubstrate at high speeds from an inkjet head nozzle into eachconfinement well. In various exemplary embodiments, the same holeconducting material can be delivered to all of the confinement wells120, 130, 140 so as to provide for depositing of the same holeconducting layer 110 within all of the confinement wells 120, 130, 140.After material is loaded into the confinement wells to form holeconducting layer 110, the display 100 can be dried to allow any carrierfluid to evaporate, a process which can include exposing the display toheat, to vacuum, or ambient condition for a set period of time.Following drying, the display may be baked at an elevated temperature soas to treat the deposited film material, for example, to induce achemical reaction or change in film morphology that is beneficial forthe quality of the deposited film or for the overall process. Thematerial associated with each organic light-emissive layer 112 can besimilarly mixed with a carrier fluid such as an organic solvent or amixture of solvents to form inkjet inks that are formulated to providereliable and uniform loading into the confinement wells. These inks canthen be inkjet deposited using an inkjet process within the appropriateconfinement wells 120, 130, 140 associated with each emission color. Forexample, the ink associated with the red organic light-emissive layer,the ink associated with the green organic light-emissive layer, and theink associated with the blue organic light-emissive layer are separatelydeposited into the corresponding confinement wells 120, 130, 140. Thediffering organic light-emissive layers 112 can be depositedsimultaneously or sequentially. After loading with one or more of theinks associated with the organic light emissive layers, the display canbe similarly dried and baked as described above for the hole conductinglayer.

While not illustrated, additional active OLED layers of material can bedisposed within the confinement well. For example, OLED display 100 canfurther include a hole injection layer, a hole transport layer, anelectron blocking layer, a hole blocking layer, an electron transportlayer, an electron injection layer, a moisture protection layer, anencapsulation layer, etc., all of which those having ordinary skill inthe art are familiar with but are not discussed in detail here.

The hole conducting layer 110 can include one or more layers of materialthat facilitates injection of holes into the organic light-emissivelayer 112. For example, hole conducting layer 110 can include a singlelayer of hole conducting material such as, for example, a hole injectionlayer. Alternatively, hole conducting layer 110 can include a pluralityof layers such as at least one of a hole injection layer, such asPoly(3,4-ethylenedioxythiophene:poly(styrenesulfonate) (PEDOT:PSS), anda hole transport layer, such asN,N′-Di-((1-napthyl)-N,N′-diphenyl)-1,1′-biphenyl)-4,4′-diamine (NPB).

The organic light-emissive layer 112 can be deposited over the holeconducting layer 110 such that organic light-emissive layer 112sufficiently conforms to the topography created by the electrodes, thespace between the electrodes, and the topography of the hole conductinglayer. The organic light-emissive layer 112 can include material tofacilitate light emission such as an organic electroluminescencematerial.

In an exemplary embodiment, the thickness of the OLED stack (e.g. allactive OLED layers deposited over the electrodes within a confinementwell) can range from 10 nm to 250 nm. For example, a hole transportlayer can having a thickness ranging from 10 nm to 40 nm; a holeinjection layer can have a thickness ranging from 60 nm to 150 nm; anorganic light-emissive layer can have a thickness ranging from 30 nm-150nm, and optionally a hole blocking layer, electron transport layer, andelectron injection layer having combined thickness ranging from 10 nm to60 nm.

In an exemplary embodiment, it is contemplated that droplets having avolume of about 10 pL or less may be used to produce each of layers 110,112. In various exemplary embodiments, droplet volumes of 5 pL or less,3 pL or less, or 2 pL or less may be used. The OLED layers 110, 112 canbe formed using from 1 to 20 droplets having the above describedvolumes.

In one exemplary and nonlimiting embodiment, the present disclosurecontemplates confinement wells arranged such that the areas of the wellsassociated with red, green, or blue light emissions 120, 130, 140 can be66 μm×66 μm for displays having a resolution of 326 ppi (e.g., Pitch=78um) where the width between neighboring wells in this embodiment can be12 μm. The area associated with red or green sub-pixel light emission ofsuch an arrangement can be 31.5 μm×31.5 μm, and the area associated withblue sub-pixel light emission can be 66 μm×30 μm, leading to an overallpixel fill factor of 65%, as compared to the fill factor of 46% for theconventional RGB side-by-side layout described with reference to FIG. 1.For another exemplary and nonlimiting embodiment, a display having aresolution of 440 ppi (e.g., Pitch=58 μm), it is contemplated to arrangeconfinement wells such that areas of the wells associated with red,green, or blue light emissions 120, 130, 140 can be 46 μm×46 μm, whereagain the width between neighboring wells in this embodiment is 12 μm.An area associated with red or green sub-pixel light emission of such adisplay structure can be 20.3 μm×20.3 μm, while an area associated withblue sub-pixel light emission can be 76 μm×49.1 μm, thereby producing afill factor of approximately 46%, as compared to the fill factor of 30%for the conventional RGB side-by-side layout described with reference toFIG. 1. In these embodiments the width between adjacent wells can be 12μm, but as discussed above, this width can take on different values, andwhile a smaller value may be desirable (to provide for a greaterproportion of the substrate area assigned to the active electrodeareas), processing constraints on the formation of the well structureand circuit layout constraints may effectively set a lower bound on thisdimension. The value of 12 μm is selected as representative for theseexamples, but one having ordinary skill in the art would appreciate thatother dimensions could be used, for example, larger dimensions like 20μm, or smaller dimensions, like 8 μm, 6 μm, or even 1 μm withoutdeparting from the scope of the present disclosure and claims. Onehaving ordinary skill in the art can further appreciate that while inthe above examples, the red, green, and blue confinement wells each haveidentical dimensions, other arrangements are possible. For example, twoconfinement wells associated with differing emission colors can have thesame dimensions and one confinement well associated with yet anotherdiffering emission color can have a differing dimension or theconfinement wells associated with each emission color can have differingdimensions.

These exemplary, non-limiting arrangements in accordance with thepresent disclosure provide for confinement wells having minimum welldimensions of greater than 45 μm even for the very high resolution caseof 440 ppi, and therefore can permit droplet volumes, for example, ofaround 10 pL, to be used, thereby simplifying manufacturing by allowingfor the use of droplet volumes that are available from existing inkjetprinting. In addition, the above exemplary, non-limiting arrangementsincrease pixel fill factor as compared to a conventional RGBside-by-side layout by about 43% and 84% for the 326 ppi and 440 ppicases respectively. More generally, the various exemplary embodiments inaccordance with the present disclosure provide enhancements in the fillfactor of high resolution displays manufactured using inkjet, such asvery high resolution displays, for which enhancements of 40% or more arepossible.

As those of ordinary skill in the art are familiar with, a commonelectrode (not shown) can be disposed over the organic light-emissivelayer 112 following deposition. After the common electrode is deposited,the resulting topography of the common electrode can sufficientlyconform to topography of organic light-emissive layer 112. The commonelectrode can be deposited using any manufacturing technique, forexample, by vacuum thermal evaporation, sputtering, chemical vapordeposition, spray coating, inkjet printing, or other techniques. Thecommon electrode can be transparent or reflective and can be formed of aconductive material such as a metal, a mixed metal, an alloy, a metaloxide, a mixed oxide, or a combination thereof. For example, indium tinoxide or a thin layer of magnesium silver. The thickness of the commonelectrode can range from approximately 30 nm to 500 nm.

In addition, the common electrode can have any shape, arrangement, orconfiguration. For example, the common electrode can be disposed as adiscrete layer associated with single sub-pixel, or a single pixel.Alternatively, the common electrode can be disposed over multiplesub-pixels or pixels, for example, over the entire pixel arrangement ofthe display 100. For instance, the common electrode can be blanketdeposited within the confinement wells 120, 130, 140 as well as over theconfinement structures 104. Additional active OLED layers (not shown forsimplicity) can be deposited onto the organic light emissive layer 112before deposition of a common electrode, such as electron transportlayers, electronic injection layers, and/or hole blocking layers. Suchadditional OLED layers can be deposited by inkjet printing, by vacuumthermal evaporation, or by another method.

In accordance with exemplary embodiments, the OLED device 100 can have atop emissive configuration or a bottom emissive configuration. Forexample, as illustrated in FIG. 3A, in a top emissive configuration,electrodes 106, 108 can be reflective electrodes and the commonelectrode that is disposed over the organic light-emissive layer can bea transparent electrode. Alternatively, in a bottom emissiveconfiguration, electrodes 106, 108 can be transparent and the commonelectrode can be reflective.

In another exemplary embodiment, the OLED display 100 can be anactive-matrix OLED (AMOLED). An AMOLED display, as compared to apassive-matrix OLED (PMOLED) display, can enhance display performance,but relies on active drive circuitry, including thin film transistors(TFTs), on the substrate and such circuitry is not transparent. WhilePMOLED displays have some elements, such as conductive bus lines thatare not transparent, AMOLED displays have substantially more elementsthat are non-transparent. As a result, for a bottom emission AMOLEDdisplay, the fill factor may be reduced compared to a PMOLED becauselight can only be emitted through the bottom of the substrate betweenthe non-transparent circuit elements. For this reason, it may bedesirable to use a top emission configuration for AMOLED displays sinceusing such a configuration may permit the OLED device to be constructedon top of such non-transparent active circuit elements. Thus, light canbe emitted through the top of the OLED device without concern for theopacity of the underlying elements. In general, using a top emissionstructure can increase the fill factor of each pixel 150 of display 100because light emission is not blocked by additional non-transparentelements (e.g. TFTs, driving circuitry components, etc.) deposited onthe substrate 102.

In addition, non-active areas of each pixel can be limited to theconfinement structures, surface features, and/or pixel definition layers(examples of which are described in further detail below) formed on thesubstrate 102. A conductive grid also can be disposed on substrate 102to prevent an undesirable voltage drop across the display 100, which canarise because the transparent top electrodes used in top emission OLEDstructures typically have low conductivities. When the common electrodeis blanket deposited within the confinement wells 120, 130, 140 and overthe confinement structures 104, the conductive grid can be disposed onnon-active portions of the substrate 102 and coupled to the commonelectrode through via holes formed in selected confinement structures104. However, the present disclosure is not limited to a top emissionactive-matrix OLED configuration. The techniques and arrangementsdiscussed herein can be used with any other type of displays such asbottom emission and/or passive displays as well as those one of ordinaryskill in the art would understand how to make using appropriatemodifications.

In an exemplary embodiment, as illustrated in FIG. 3A, each confinementwell can include a plurality of active sub-pixel regions that span W1and W2, respectively, and are separated by gap S, and are confinedwithin a well having width CW. The dimensions, W1, W2, and CW areprimarily related to pixel pitch, which correlates to the resolution(e.g. 326 ppi, 440 ppi) of the display. The dimension of the gap S isrelated to restrictions associated with fabrication techniques andprocesses, and layout. In general, it may be desirable to minimize thedimension associated with the gap S. For example, 3 μm may be a minimumdimension; however, one of ordinary skill in the art would appreciatethat dimensions from as small as 1 μm to greater than 10 μm arepossible. The height H of confinement structures 104 is also related toprocessing restrictions rather than a particular display layout orresolution. While an exemplary value of the height H of confinementstructures 104 may be 1.5 μm, the height H, can range from 0.5 μm to 5μm in various exemplary embodiments. Referring to FIG. 3B, BW is thewidth of the confinement structures 104 between adjacent wells (e.g.,wells 120 and 130 in FIG. 3B). As described above, it may be desirableto minimize this dimension and an exemplary value is 12 μm. However, oneof ordinary skill would understand that this value can be arbitrarilylarge (e.g. hundreds of microns) in some instances, and can also be assmall as 1 μm, depending on fabrication techniques and processes thatmay permit such a small value for BW.

Referring now to FIG. 4, a cross-sectional view of an exemplaryembodiment of a confinement well 220 of a display 200 is illustrated.The arrangement of FIG. 4 is similar to that described above withreference to FIG. 3A, with like numbers used to represent like elementsexcept using the 200 series as opposed to the 100 series. Asillustrated, however, the OLED display 200 also includes an additionalsurface feature 216 disposed in the gap S between electrodes 206, 208.

Surface feature 216 can be any structure that does not directly provideelectrical current into the OLED films disposed over it, therebycomprising a non-active region of the pixel area between the activeregions associated with the electrodes 206 and 208. For example, thesurface feature 216 can further comprise an opaque material. As depictedin FIG. 4, a hole conducting layer 210 and organic light-emissive layer212 can be deposited over a portion of such circuitry elements, asrepresented topographically by surface feature 216. In the case thatsurface feature 216 contains electrical elements, such elements may befurther coated with an electrically insulating material so as toelectrically isolate those elements from the OLED films deposited ontosurface feature 216.

In an exemplary embodiment, surface feature 216 can include drivingcircuitry, including but not limited to, for example, an interconnect,bus lines, transistors, and other circuitry with which those havingordinary skill in the art are familiar. In some displays, drivingcircuitry is disposed proximal to the active region of the pixel drivenby such circuitry to minimize complicated interconnections and to reducethe voltage drop. In some cases, the confinement well would surround anindividual sub-pixel, and such circuitry can be outside the confinementwell region such that the circuitry would not be coated with active OLEDlayers. However, in the exemplary embodiment of FIG. 4, as well asothers described herein, because the confinement well 220 can contain aplurality of sub-pixels that are associated with differing pixels, suchdriving circuitry elements can be provided within the confinement wells,which may optimize the electrical performance of the drive electronics,optimize drive electronics layout, and/or optimize the fill factor.

The hole conducting layer 210 and organic light emissive layer 212 canbe deposited (as previously discussed, for example, with reference toFIGS. 3A and 3B) into the region defined by confinement well structures204 and over the surface feature 216 such that layers 210, 212sufficiently conform to underlying surface feature topographies and havea substantially uniform thickness in the confinement well, leading tolayers 210 and 212 having non-planar top surfaces. In the configurationwherein surface feature 216 extends above the plane of the top surfaceof the electrode a distance greater than the thickness of one or both ofthe layers 210 and 212, then one or both of those layers will also bediscontinuous in a plane parallel to the plane of the display within thewell 220. Thus, one or both layers 210, 212 will be non-planar anddiscontinuous in a plane parallel to the plane of the display due to theprotrusion associated with the surface feature 216. As above, this isillustrated, for example, by the dashed line illustrating a plane P thatis coplanar with the surface of 212 that is disposed over the electrodes206, 208. As shown, the layer 212 is not planar across the entireconfinement well and instead sufficiently conforms to the underlyingtopographies such that the layer 212 has an overall non-planar topsurface due to the gap region S and protrusion 216. In other words, oneor both of the layers 210, 212 will rise and fall across the confinementwell to sufficiently conform to the existing topography of the wellprior to the deposition of the layers 210, 212.

While the surface feature 216 is illustrated in FIG. 4 as having athickness greater than the electrodes, the surface feature 216 canalternatively have a thickness less than or equal to the electrodes.Moreover, while surface feature 216 is illustrated in FIG. 4 as beingdisposed on substrate 202, surface feature 216 can be further disposedover one or both of electrodes 206, 208. Surface feature 216 can differfor each confinement well in the array and not all confinement wellshave to include a surface feature. Surface feature 216 can furtherfunction as a pixel definition layer where the non-transparentproperties of surface feature 216 can be used to define portions ofsub-pixels or overall pixel arrangements.

Referring now to FIGS. 5A and 5B, partial cross-sectional views ofanother exemplary embodiment of a display confinement well in accordancewith the present disclosure is illustrated. The arrangement of FIGS. 5Aand 5B is similar to that described above with reference to FIGS. 3A and3B, with like numbers used to represent like elements except using the300 series as opposed to the 100 series. As illustrated in FIGS. 5A and5B, however, the OLED display 300 also includes a definition layer 314.Definition layer 314 can be deposited on substrate 302 where confinementstructures 304 can be disposed over the definition layer 314. Inaddition, definition layer 314 can be disposed over a non-active portionof electrodes 306, 308. Definition layer 314 can be any physicalstructure having electrically insulating properties used to defineportions of OLED display 300. In an embodiment, definition layer 314 canbe a pixel definition layer that can be any physical structure used todelineate pixels within the pixel array. Definition layer 314 can alsodelineate sub-pixels.

As illustrated, in an exemplary embodiment, the definition layer 314 canextend beyond the confinement structures 304 to over a portion ofelectrodes 306, 308. Definition layer 314 can be made of an electricallyresistant material such that the definition layer 314 prevents currentflow and thus can reduce unwanted visual artifacts by substantiallypreventing light emission through the edges of the sub-pixel. Definitionlayer 314 can also be provided to have a structure and chemistry tomitigate or prevent the formation of non-uniformities where the OLEDfilms coat over the edge of the definition layer. In this way,definition layer 314 can assist in masking film non-uniformities formedaround surface features that would otherwise be included in the activeregions of the pixel area and then contribute to pixel non-uniformity;such non-uniformities could occur, for example, at the exterior edges ofeach sub-pixel where the OLED films contact the confinement well, or atthe interior edges of the each sub-pixel where the OLED films contactthe substrate surface.

The hole conducting layer 310 and the organic light-emissive layer 312can each be deposited within the region defined by the confinementstructure 304 and over the pixel definition layers so as to form acontinuous layer within the confinement well 320. As described abovewith respect to FIGS. 3A and 3B, the layers 310, 312 can sufficientlyconform to the overall topography of the confinement well, and thus mayhave non-planar surfaces and/or be discontinuous in a plane of thedisplay, as illustrated for example by plane P in FIG. 5A. As explainedabove with reference to exemplary embodiment of FIG. 3A, the thicknessof the hole conducting layer 310 and the organic light-emissive layer312 can be substantially uniform, as described above.

In an exemplary embodiment, as illustrated in FIG. 5A, each confinementwell can include a plurality of active sub-pixel regions including W1and W2 separated by gap S and contained within a confinement well havingwidth CW, with W1, W2, and CW being primarily related to the pixelpitch, as discussed above with reference to FIG. 3A. Similarly, thedimension of the gap S is related to fabrication and processingtechniques, and layout, wherein S may range in exemplary embodimentsfrom 1 m to greater than 10 μm, with, 3 μm being an exemplary dimensionfor S. The height H of confinement structures 304 may be as describedabove with reference to FIG. 3A. Referring to FIG. 5B, BW is, asdescribed above, the width of the confinement structures 304 betweenadjacent wells and can be selected as described above with reference toFIG. 3B.

The dimension T associated with the thickness of the definition layercan be variable based on fabrication techniques and processingconditions, and the type of definition layer material that is used. Invarious exemplary embodiments, the dimension T associated with thethickness of the definition layer can range from 25 nm to 2.5 μm, butfrom 100 nm to 500 nm can be considered the most typical range. Thedimensions labeled B1, B2 in FIG. 5A and B1, B1′ in FIG. 5B, associatedwith the extension of the definition layer beyond the edge of theconfinement structure 104 within the confinement wells, can be selectedas desired. However, a larger dimension may contribute to a reduction infill factor by reducing the amount of available active pixel electrodearea. Therefore, it may be desirable to select the minimum dimensionthat will serve the desired function, which is generally to exclude edgenon-uniformities from the active electrode area. In various exemplaryembodiments, this dimension can range from 1 μm to 20 μm, and may, forexample, range from 2 μm to 5 μm.

With reference now to FIG. 6, a cross-sectional view of an exemplaryembodiment of a confinement well 420 of a display 400 is illustrated.The arrangement of FIG. 6 is similar to that described above withreference to FIGS. 5A and 5B, with like numbers used to represent likeelements except using the 400 series as opposed to the 300 series. Asshown, however, the OLED display 400 also includes an additionaldefinition layer 416 disposed in the gap S between electrodes 406, 408.As shown in FIG. 6, the definition layer 416 can be a surface featurethat has a somewhat differing structure than the surface feature of FIG.4 in that a portion of the additional definition layer 416 extendsthroughout the gap S on the substrate 402 and over portions ofelectrodes 406, 408 adjacent the gaps. The additional definition layer416 can have any topography, with the one illustrated in FIG. 6 beingexemplary only. As illustrated in FIG. 6, a notch 417 can be present inthe surface of the additional definition layer 416 that faces away fromthe substrate 102. The notch 417 can be formed using various methods.For example, notch 417 may result from the manufacturing process suchthat during deposition of the additional definition layer 416, the layer416 can generally conform to any topography present within theconfinement well such as electrodes 406, 408 where notch 417 is formedby the differing thickness between a substantially uniform thicknessover the electrodes 406, 408 and a substantially non-uniform thicknesswith surfaces not associated the top surface of electrodes 406, 407.Alternatively, notch 417 can be omitted and the top surface ofadditional definition layer 416 can have a substantially planartopography, for instance, in the case that the additional definitionlayer 416 is deposited using a non-conformal deposition method such thatthe underlying surface topography is smoothed out.

In either configuration, the hole conducting layer 410 and/or theorganic light-emissive layer 412 can be deposited (as previouslydiscussed, for example, with reference to FIGS. 3A and 3B) such thatlayers 410, 412 sufficiently conform to the topography of the additionaldefinition layer 416 and have a substantially uniform thickness, as hasbeen described above.

The distance between the top surface (i.e., the surface facing away fromthe substrate) of the additional definition layer 416 and the substrate402 can be greater than or less than the distance between the topsurface of the electrodes 406, 408 and the substrate 402. Alternatively,the distance between the top surface of the additional definition layer416 and the substrate 402 can be substantially equal to the distancebetween the top surface of the electrodes 406, 408 and the substrate402. In other words, the thickness of the additional definition layer416 can be such that it ranges from being positioned between the topsurface of the substrate and the top surfaces of the surroundingconfinement structures 404, or such that it substantially lies in thesame plane as the top surfaces of the confinement structures 404.Alternatively, the additional definition layer 416 can be substantiallythe same height as the electrodes 406, 408 such that the additionaldefinition layer 416 does not overlap a portion of the electrodes 406,408, but rather fills in the gap S between them.

Hole conducting layer 410 and organic light-emissive layer 412 can bedisposed over the portions of definition layer 414 that extend beyondthe confinement structure 404 and into the well 420, and the layers 410,412 can extend over the additional definition layer 416 within theconfinement well 420 defined by confinement structure 404. Theadditional definition layer 416 can be made of an electrically resistantmaterial such that the additional definition layer 416 can preventcurrent flow and thus may reduce undesirable visual artifacts bypreventing light emission through the edges of the sub-pixel. Thedefinition layer 414 and the additional definition layer 416 can be madeof the same or differing materials.

In an exemplary embodiment, as illustrated in FIG. 6, each confinementwell can include a plurality of active sub-pixel regions including W1and W2 separated by gap S and contained within a confinement well havingwidth CW, with W1, W2, CW, and S being primarily related to the pixelpitch, as discussed above. As above, 3 μm may be a minimum dimension forS, but one of ordinary skill in the art would appreciate that dimensionsfrom as small as 1 μm to even greater than 10 μm are possible. Theheight H of confinement structures 404 can be chosen and with the rangesas described above with reference to FIGS. 3A and 3B, for example.

The dimension T1 associated with the thickness of the definition layerand the dimension T2 associated with the thickness of the additionaldefinition layer can be variable based on fabrication techniques,processing conditions and the type of definition layer material that isused. As a result, the dimension T1 associated with the thickness of thedefinition layer and the dimension T2 associated with the thickness ofthe additional definition layer can range from 50 nm to 2.5 μm, forexample, from 100 nm to 500 nm. The dimensions SB1, SB2, and B2associated with the extension of the definition layer inside the edge ofthe confinement well can be selected as desired. However, a largerdimension will contribute to a reduction in fill factor by reducing theamount of available active pixel electrode area. Therefore, it may bedesirable to select the minimum dimension that will serve the desiredfunction, which is generally to exclude edge non-uniformities from theactive electrode area. In various exemplary embodiments, this dimensioncan range from 1 μm to 20 μm, and may for example range from 2 μm to 5μm.

As those having ordinary skill in the art would appreciate based on thepresent disclosure, any of the disclosed definition layer configurationscan be used in any combination of differing ways to achieve a desirablepixel definition configuration. For example, definition layer 414 and/oradditional definition layer 416 can be configured to define any pixeland/or a sub-pixel region or any partial pixel and/or sub-pixel regionwhere definition layer 414 can be associated a definition layerdeposited under any confinement structures 404 and additional definitionlayer 416 can be associated with any definition layer deposited within aconfinement well between electrodes such as in confinement well 420. Anartisan of ordinary skill would recognize that the cross-sections shownwithin the present disclosure are merely illustrative cross-sections andtherefore the present disclosure is not to be limited to the specificcross-sections illustrated. For instance, while FIGS. 3A and 3B areillustrated along line 3A-3A and 3B-3B respectively, a differentcross-sectional view, taken along a different line, for exampleincluding in directions orthogonal to 3A-3A and 3B-3B, may reflectdiffering definition layer configurations. In an exemplary embodiment,definition layers can be used in combination to outline a pixel, such aspixels 150, 151, 152 illustrated in FIG. 2. Alternatively, definitionlayers can be configured to define a sub-pixel such that the definitionlayers completely or partially surround a sub-pixel electrode within aconfinement well.

Referring now to FIG. 7, a cross-sectional view of yet another exemplaryembodiment is illustrated. OLED display 500 can include surface feature516 and a definition layer 514. The arrangement of FIG. 7 is similar tothat described above with reference to FIG. 4, with like numbers used torepresent like elements except using the 500 series as opposed to the200 series. As illustrated in FIG. 7, however, OLED display 500 furtherincludes a definition layer 514 disposed under confinement structures504. The definition layer 514 can be any physical structure used todefine portions of OLED display 500. In an embodiment, definition layer514 can be a definition layer that can be any physical structure used todelineate pixels within the pixel array and/or sub-pixels with a pixel.As illustrated, in an exemplary embodiment, the definition layer 514 canextend beyond the confinement structure 504 and over a portion ofelectrodes 506, 508. Definition layer 514 can be made of an electricallyresistant material such that the definition layer 514 prevents currentflow and thus can reduce unwanted visual artifacts by preventing lightemission through the edges of the sub-pixel. In this way, definitionlayer 514 can assist in masking film layer non-uniformities formed atthe edge of each sub-pixel that may occur due to edge drying effects.The hole conducting layer 510 and the organic light-emissive layer 512can be deposited (as previously discussed, for example, with referenceto FIGS. 3A and 3B) such that layers 510, 512 sufficiently conform tounderlying surface feature topographies and have a substantially uniformthickness, as has been described above.

Those having ordinary skill in the art would appreciate that the variousarrangements and structures, e.g. surface features, definition layers,etc., are exemplary only and that various other combinations andarrangements may be envisioned and fall within the scope of the presentdisclosure.

Referring now to FIGS. 8-11, partial cross-sectional views of thesubstrate exhibiting various exemplary steps during an exemplary methodof manufacturing an OLED display 600 are illustrated. While the methodof manufacturing will be discussed below with reference to display 600,any and/or all of the steps described can be used in manufacturing otherOLED displays, for example OLED displays 100, 200, 300, 400, and 500described above. As illustrated in FIG. 8, electrodes 606, 608 andsurface features 616 can be provided over substrate 602. The electrodes606, 608 and surface features 616 can be formed using any manufacturingmethod such as inkjet printing, nozzle printing, slit coating, spincoating, vacuum thermal evaporation, sputtering (or other physical vapordeposition method), chemical vapor deposition, etc., and any additionalpatterning not otherwise included in the deposition technique can beachieved by using shadow masking, photolithography (photoresist coating,exposure, development, and stripping), wet etching, dry etching,lift-off, etc. The electrodes 606, 608 can be formed simultaneously withsurface features 616 or sequentially with either the electrodes or thesurface features being formed first.

Definition layer 614 and additional definition layer 618 can then bedeposited over the surface features 616 and electrodes 606, 608, asillustrated in FIG. 9. Layers 614 and 618 can be formed using anymanufacturing method, such as inkjet printing, nozzle printing, slitcoating, spin coating, vacuum thermal evaporation, sputtering (or otherphysical vapor deposition method), chemical vapor deposition, etc., andany needed additional patterning not otherwise included in thedeposition technique can be achieved by using shadow masking,photolithography (photoresist coating, exposure, development, andstripping), wet etching, dry etching, lift-off, etc. Definition layer614 can be formed simultaneously with additional definition layer 618 orthe layers 614, 618 can be formed sequentially with either layer 614 or618 being formed first.

Confinement structures 604 are provided over definition layers 614. Theconfinement structures 604 can be formed to define confinement wells 620that surround a plurality of sub-pixel electrodes 606, 608 whilespanning a plurality of pixels. The confinement structures 604 can beformed using any manufacturing method, such as inkjet printing, nozzleprinting, slit coating, spin coating, vacuum thermal evaporation,sputtering (or other physical vapor deposition method), chemical vapordeposition, etc., and any additional patterning not otherwise includedin the deposition technique can be achieved by using shadow masking,photolithography (photoresist coating, exposure, development, andstripping), wet etching, dry etching, lift-off, etc. In one exemplarytechnique, as illustrated in FIG. 10, confinement structure material canbe deposited over substrate 602 in a continuous layer 604′ and the layercan then be patterned using a mask 607 such that a portion 605 of layer604′ can be removed to expose the sub-pixel electrodes 606, 608. Theconfinement structures 604 are formed by the material of layer 604′remaining after portions 605 are removed. Alternatively, confinementstructures 604 can be formed by actively depositing material to formonly the confinement structure such that the deposited confinementstructure 604 can define boundaries and the confinement wells are formedwithin the boundaries of the deposited confinement structures 604.

In an exemplary embodiment, as illustrated in FIG. 10, each confinementwell can include a plurality of active sub-pixel regions including W1and W2 separated by gap S. As above, the dimensions, W1, W2, and CW areprimarily related to the pixel pitch. And the dimension of the gap S isrelated to restrictions associated with fabrication techniques andprocessing, and layout, and may range from 1 μm to even greater than 10μm, with 3 μm being an exemplary minimum dimension. The dimensions SB1and SB2 associated with the extension of the definition layer inside theedge of the confinement well can be selected as desired. However, alarger dimension will contribute to a reduction in fill factor byreducing the amount of available active pixel electrode area. Therefore,it may be desirable to select the minimum dimension that will serve thedesired function, which is generally to exclude edge non-uniformitiesfrom the active electrode area. In various exemplary embodiments, thisdimension can range from 1 μm to 20 μm, and may for example range from 2μm to 5 μm.

As illustrated in FIG. 11, a hole conducting layer 610 can then bedeposited using inkjet printing within the confinement well 620. Forexample, inkjet nozzle 650 can direct droplet(s) 651 of hole conductingmaterial within a target area defined within the confinement well 620.The hole conducting layer 610 may further comprise two discrete layers,for example, a hole injection layer and a hole transporting layer, andthese layers can be sequentially deposited by an inkjet method asdescribed herein. In addition, organic light-emissive layer 612 can bedeposited using inkjet printing within the confinement well 620 over thehole conducting layer 610. Inkjet nozzle 650 can direct droplet(s) 651of organic light-emissive material within a target area over the holeconducting layer 610. One of ordinary skill in the art would appreciatethat while a single nozzle is discussed with reference to FIG. 11,multiple nozzles can be implemented to provide droplets containing holeconducting material or organic light-emissive material within aplurality of confinement wells. As those of ordinary skill in the artare familiar with, in some embodiments, the same or differing colors oforganic light-emissive material can be deposited from multiple inkjetnozzle heads simultaneously. In addition, droplet ejection and placementon the target substrate surface can be performed using technology knownto those of ordinary skill in the art.

In an exemplary embodiment, a single organic light-emissive layer 612can be deposited within confinement well 620 such as a red, green, orblue layer. In an alternative exemplary embodiment, a plurality oforganic light emissive layers can be deposited within confinement well620, one over the other. Such an arrangement can work, for example, whenthe light emissive layers have differing light emissive wavelengthsranges such that when one light emissive layer is activated to emitlight, the other light emissive layer does not emit light or interferewith the light emission of the first organic light-emissive layer. Forexample, a red organic light-emissive layer or a green organiclight-emissive layer can be deposited within confinement well 620 andthen a blue organic light-emissive layer can be deposited over the redor green organic light-emissive layer. In this way, while a confinementwell can include two different light-emissive layers, only one lightemissive-layer is configured to emit light within the confinement well.

Layers 610 and 612 can be deposited so as to sufficiently conform to thetopography of definition layer 614, surface structure 616, additionaldefinition layer 618, and electrodes 606, 608, as has been describedabove, and can have a substantially uniform thickness as describedabove.

The various aspects described above with reference to FIGS. 3A-11 can beused for a variety of pixel and sub-pixel layouts in accordance with thepresent disclosure, with FIG. 2 being one exemplary and nonlimiting suchlayout. Various additional exemplary layouts contemplated by the presentdisclosure are depicted in FIGS. 12-18. The various exemplary layoutsillustrate that there are many ways to implement the exemplaryembodiments described herein; in many cases, the selection of anyparticular layout is driven by various factors, such as, for example,the underlying layout of the electrical circuitry, a desired pixel shape(which are depicted as rectangular and hexagonal shape in theillustrated embodiments, but can be other shapes as well, such aschevrons, circles, hexagons, triangles, and the like), and factorsrelated to visual appearance of the display (such as visual artifactsthat can be observed for differing configurations and for differingtypes of display content, such as text, graphics, or moving video).Those having ordinary skill in the art would appreciate that a number ofother layouts fall within the scope of the present disclosure and can beobtained through modification and based on the principles describedherein. Further, those having ordinary skill in the art would understandthat although for simplicity only the confinement structures that definethe confinement wells are described below in the descriptions of FIGS.12-18, any of the features, including surface features, circuitry, pixeldefinition layers, and other layers, described above with reference toFIGS. 3A-11 can be used in combination with any of the pixel layoutsherein.

FIG. 12 depicts a partial plan view of an exemplary embodiment of pixeland sub-pixel layout for an OLED display 700, and is similar to thelayout of FIG. 2 with further aspects of the layout being describedbelow. A confinement structure 704, for example, a bank structure, asdiscussed above can be provided on a substrate to define a plurality ofconfinement wells 720, 730, 740 in an arrayed configuration. Eachconfinement well 720, 730, 740 can include a substantially continuouslayer of OLED material (indicated by the shaded regions) such that theorganic layer extends through the confinement well 720, 730, 740 to theconfinement structure 704 surrounding the confinement well, for example,edges of the layer of OLED material in each well 720, 730, 740 maycontact the confinement structure 704. OLED layers can include, forexample, one or more of hole injecting materials, hole transportingmaterials, electron transporting materials, electron injectingmaterials, hole blocking materials, and organic light emissive materialsproviding for emission of differing light-emissive wavelength ranges.For example, confinement well 720 can include an organic light-emissivelayer associated with light emission within the red wavelength range andis indicated by R, confinement well 730 can include an organiclight-emissive layer associated with light emission within the greenwavelength range indicated by G, and confinement well 740 can include anorganic light-emissive layer associated with light emission within theblue wavelength range indicated by B. The wells 720, 730, 740 can have avariety of arrangements and configurations, including with respect toeach other (e.g., layouts). For example, as illustrated in FIG. 12,confinement wells 720 and confinement wells 730 that respectivelycontain red organic light-emissive layer R and green organiclight-emissive layer G are disposed in rows R₁, R₃ in an alternatingarrangement. Alternating with the rows R₁ and R₃ are rows R₂, R₄ of theconfinement wells 740 that contain blue organic-light emissive layer B.Confinement wells 720, 730 also can be alternatively arranged within therows R₁, R₃.

A plurality of electrodes 706, 707, 708, 709; 736, 737, 738, 739; and742, 744 can be disposed in each confinement well 720, 730, 740,respectively, wherein each electrode can be associated with a sub-pixelassociated with a particular light emission color such as red, green, orblue light emission. A pixel 750, 751, 752, 753, identified in FIG. 12by dashed lines, can be defined to include one sub-pixel having redlight emission, one sub-pixel having green light emission, and onesub-pixel having blue light emission. For example, each confinement well720, 730, 740 can respectively include a plurality of electrodes 706,707, 708, 709; 736, 737, 738, 739; and 742, 744 configured such thattheir associated electrode active regions correspond to the electrodeoutlines shown in FIG. 12, are spaced apart from each other. Confinementwells 720, 730, 740 can have a differing number and/or arrangement ofelectrodes within the confinement well. Alternatively, additionalarrangements are possible, such as arrangements with other sets ofcolors than red, green, and blue, including combinations of colorsinvolving more than three sub-pixel colors. Other arrangements are alsopossible in which more than one sub-pixel of a single color isassociated with a particular pixel, for example, each pixel can haveassociated with it one red, one green, and two blue sub-pixels, or othercombinations of numbers of sub-pixels of a particular color and othercombinations of colors. Moreover, if multiple layers of differinglight-emissive material are positioned over each other, it iscontemplated that differing color sub-pixels may overlap each other. Asillustrated in FIG. 12, sub-pixel electrodes can be spaced apart fromstructures that define the confinement wells. In an alternativeembodiment, the sub-pixel electrodes can be deposited such that they aredirectly adjacent to the confinement well structures such that no gapoccurs between the electrode and the confinement structure. In addition,the confinement well structures can be disposed over a portion of thesub-pixel electrodes.

In addition, adjacent confinement wells can have differing sub-pixelarrangements. For example, as illustrated in FIG. 12, confinement wells720 and 730 include a 2×2 active electrode region arrangement, andconfinement well 740 includes a 1×2 active electrode region arrangement,with the active electrode regions in the 2×2 arrangements being squaresof the same size and the active electrode regions in the 1×2 arrangementbeing rectangles of the same size. As noted above, electrodes withindiffering confinement wells can have differing surface areas of activeregions.

In one exemplary arrangement, the active regions associated with theelectrodes used to address sub-pixels of light-emission within the bluewavelength range B can have a greater surface area than the activeregions associated with the electrodes used to address light-emissionwithin the red and/or green wavelength range R, G. It may be desirablefor the active regions of the electrodes associated with the sub-pixelshaving light-emission in the blue wavelength range B to have a greatersurface area than the active regions associated with a sub-pixelelectrode associated with a red or green light emission becausesub-pixels associated with blue light emission often have substantiallyshorter lifetimes than sub-pixels associated with having red or greenlight emission when operating at the same area brightness levels.Increasing the relative active area of the sub-pixels associated withblue light emission enables operation at relatively lower areabrightness levels while still maintaining the same overall displaybrightness, thereby increasing the lifetime of the sub-pixels associatedwith blue light emission and the overall lifetime of the display. It isnoted that sub-pixels associated with red and green light emission maybe correspondingly reduced in relation to the sub-pixel associated withblue light emission. This can lead to the sub-pixels associated with redand green light-emission to be driven at a higher brightness level inrelation to a sub-pixel associated with blue light-emission which canreduce the red and green OLED device lifetime. However, the lifetimes ofthe sub-pixels associated with red and green light emission can besignificantly longer than the lifetime associated with the sub-pixelassociated with the blue sub-pixel that the sub-pixel associated withthe blue light emission remains the limiting sub-pixel with respect tothe overall display lifetime. While the active regions of the electrodeswithin confinement well 740 are illustrated as being arranged with theirelongate direction extending horizontally in FIG. 12, the electrodescould alternatively be arranged such that their elongate directionextends vertically in FIG. 12.

Intervals between adjacent confinement wells can be equal throughout thepixel layout or can vary. For example, with reference to FIG. 12, aninterval b′ between confinement wells 720, 730 can be greater than orequal to the interval f′ between confinement wells 720 or 730 and 740.In other words, the horizontal interval between adjacent confinementwells in a row may differ from the vertical interval between adjacentconfinement wells in adjacent rows, in the orientation of FIG. 12.Moreover, the horizontal interval b′ in rows R₁, R₃ may be equal to ordiffer from the horizontal interval a′ in R₂, R₄.

Spacing (gaps) between the active regions of the electrodes within eachof the differing confinement wells 720, 730, 740 also can be the same ordiffer and may vary depending on the direction of spacing (e.g.,horizontal or vertical). In one exemplary embodiment, the gaps d and ebetween the active regions of the electrodes within the confinementwells 720, 730 can be the same and can differ from the gap betweenactive regions of the electrodes within the confinement well 740.Further, in various exemplary embodiments, the gaps between adjacentactive electrode regions within a confinement well are less than thegaps between adjacent active electrode regions in neighboringconfinement wells, either in the same or differing rows. For example, c,d, and e may each be less than either a, b, or f in FIG. 12.

In FIG. 12 there is shown a gap between the interior edges of eachconfinement well, e.g. 720, and the exterior edges of each of the activeelectrode regions associated within that confinement well, e.g. 706,707, 708, 709. However, as illustrated in FIG. 2, according to variousexemplary embodiments, such a gap may not be present and the exterioredge of each of active electrode regions may be the same as the interioredge of the confinement well. This configuration can be achieved, forexample, using a structure like the one illustrated in FIG. 3A, wherethe configuration show in FIG. 12, in which such a gap is present, canbe achieved, for example, using a structure like the one illustrated inFIG. 5A. However, other structures may also be able to achieve the sameconfigurations illustrated in FIGS. 2 and 12.

Pixels 750, 751, 752, 753 can be defined based on the confinement wellarrangement and corresponding sub-pixel layout. The overall spacing, orpitch, of pixels 750, 751, 752, 753 can be based on the resolution ofthe display. For example, the higher the display resolution, the smallerthe pitch. In addition, adjacent pixels can have differing sub-pixelarrangements. For example, as illustrated in FIG. 12, pixel 750 includesa red sub-pixel R in the top left portion, a green sub-pixel G in thetop right portion, and a blue sub-pixel B in spanning the majority ofthe bottom portion of the pixel. The sub-pixel layout of pixel 751 issimilar to that of pixel 750 except the relative positions of the greensub-pixel G and the red sub-pixel R being switched, with the greensub-pixel G in the top left portion, a red sub-pixel R in the top rightportion. Pixels 752 and 753, which are adjacent and underneath pixels751, 750 respectively, are mirror images of pixels 751 and 750,respectively. Thus, pixel 752 includes a blue sub-pixel B in the topportion, a green sub-pixel G in the bottom left portion, and a redsub-pixel R in the bottom right portion. And pixel 753 includes a bluesub-pixel in the top portion, a green sub-pixel in the bottom leftportion, and a red sub-pixel in the bottom right portion.

In an exemplary embodiment for a high resolution display according toFIG. 12 and having 326 pixels per inch (ppi), a pixel including a redsub-pixel, a green sub-pixel, and a blue sub-pixel can have overalldimensions of approximately 78 μm×78 μm, corresponding to the overallpitch of the display needed to achieve 326 ppi. Assuming for thisembodiment that a′=b′=f′=12 μm, reflecting, as previously discussed, thestate of the art minimum spacing between confinement regions, furtherassuming that a=b=f=12 μm+6 μm=18 μm, reflecting a case in which adefinition layer is utilized that extends 3 μm inside the confinementwell edge, and finally assuming c=d=e=3 μm as a typical gap betweenelectrode active regions within a confinement well, the areas associatedwith each of the red and green sub-pixels can be 28.5 μm×28.5 μm and thearea associated with the blue sub-pixels can be 60 μm×27 μm. The surfacearea of the blue sub-pixels can be greater than each of the red andgreen sub-pixels to increase overall display lifetime as describedabove. Such a layout can have confinement wells associated withgroupings of 2×2 red and green sub-pixels having dimensions of 66 μm×66μm, and confinement wells associated with groupings of 1×2 bluesub-pixels having dimensions of 66 μm×66 μm. Such dimensions provide forstraightforward loading of active OLED material with conventional inkjetprint heads and printing systems while also providing for a highresolution display with high fill factor of greater than 50%, such as53%. Such dimensions also provide for such features in a structurehaving a definition layer that can provide for enhanced film uniformitywithin the active electrode region by blocking current flow through thefilm region immediately adjacent to the confinement well wall.

In a corresponding exemplary embodiment for a high resolution displayhaving 440 pixels per inch (ppi) a pixel including a red sub-pixel, agreen sub-pixel, and a blue sub-pixel can have an overall dimension ofapproximately 58 μm×58 μm where assuming the same value for thedimensions a, b, c, d, e, f, a′, b′, and f′ as in the immediatelyprevious example, the area associated with each of the red and greensub-pixels can be 18.5 μm×18.5 μm and the area associated with the bluesub-pixels can be 40 μm×17 μm. The surface area of the blue sub-pixelscan be greater than each of the red and green sub-pixels to increaseoverall display lifetime as described above. Such a layout can haveconfinement wells associated with groupings of 2×2 red and greensub-pixels having dimensions of 46 μm×4 μm, and confinement wellsassociated with groupings of 1×2 blue sub-pixels having dimensions of 46μm×46 μm. Such dimensions provide for relatively straightforward loadingof active OLED material with conventional inkjet print heads andprinting systems while also providing for a high resolution display withhigh fill factor of 40%.

In each of the above exemplary embodiments, various values for thedimensions a, b, c, d, e, f, a′, b′, f′ can be implemented. However, oneof ordinary skill in the art would recognize that these dimensions vary.For example, the spacing between confinement walls (a′, b′, f′) can bevaried, as previously discussed from as little as 1 μm to as large ashundreds of microns for large ppi. The gap between active electroderegions within a confinement well (c, d, e) can vary, as discussedabove, from as little as 1 μm to as large as tens of microns. The gapbetween the active electrode regions and the edge of the confinementwalls (effectively half the difference between a′ and a, b′ and b′ andf′ and f, respectively) can also vary, as discussed above, from aslittle as 1 μm to as large as 10 μm. Furthermore, as these dimensionsare varied, they apply constraints, along with the ppi (that determinesthe overall pitch of the display), that limit the range of valuesallowed for the confinement well dimensions and the active electroderegions contained therein. In the above exemplary embodiments, forsimplicity, square confinement wells of the same dimension are used forall three colors. However, the confinement wells need not be square, andneed not all be the same size. In addition, the dimensions provided forin FIG. 12 indicate various common dimensions, for example, the gapbetween active electrode regions within the red confinement wells andthe green confinement wells, but in some exemplary embodiments, thosegaps are not common dimensions but differ from each other.

FIG. 13 depicts a partial plan view of another exemplary pixel/sub-pixellayout of an OLED display 800. Features common to previously discussedexemplary embodiments are not described. For simplicity, differenceswill be discussed.

Display 800 can have a greater separation between the active regionsassociated with sub-pixel electrodes within a confinement well than forexample, sub-pixel electrodes of display 700 as illustrated in FIG. 12.Spacing between adjacent active regions associated with electrodes 806,807, 808, 809; 836, 837, 838, 839; and 842, 844 within respectiveconfinement wells 820, 830, 840 can be greater than an interval betweenadjacent active electrode regions in adjacent confinement wells. Forexample, the active regions associated with electrode 836 can be spacedapart from one another a predetermined distance g, and similarly for theactive regions associated with electrode 838. The interval k betweenadjacent active electrode regions in neighboring confinement wells 820,830 can be less than the interval g between the active regionsassociated with electrodes 836, 838, and the interval m between theactive regions associated with electrode 842 (and similarly forelectrode 844) can be greater than the interval n between the adjacentactive electrode regions in neighboring confinement well 840 andconfinement wells 820, 830. Such spacing can provide for greater spacingbetween sub-pixel electrodes disposed within a confinement well andassociated with the same light emission color while providing for acloser arrangement of sub-pixel electrodes associated with a singledefined pixel. This spacing can reduce undesirable visual artifacts suchthat the display appears to be an array of closely arranged RGB tripletsand not an array of closely arranged RRRR quadruplets, GGGG quadruplets,and BB pairs.

Another exemplary pixel/sub-pixel layout for a display in accordancewith the present disclosure is depicted in FIG. 14. A confinementstructure 904 can be provided on a substrate to define a plurality ofconfinement wells 920, 930, 940 in an arrayed configuration. Eachconfinement well 920, 930, 940 can include a substantially continuouslayer of OLED material (indicated by the shaded regions) such that edgesof the organic layer extends throughout the confinement well 920, 930,940 to the confinement structure 904 surrounding the confinement well,for example, edges of the layer of OLED material in each well 920, 930,940 may contact the confinement structure 904. Active OLED layers caninclude, for example, without limitation, one or more of hole injectingmaterials, hole transporting materials, electron transporting materials,electron injecting materials, hole blocking materials, and organic lightemissive materials providing for emission of differing light-emissivewavelength ranges. For example, confinement well 920 can include anorganic light-emissive layer associated with light-emission within thered wavelength ranges range R, confinement well 930 can include anorganic light-emissive layer associated with light-emission within thegreen wavelength range G, and confinement well 940 can include anorganic light-emissive layer associated with light-emission within theblue wavelength range B. The organic light-emissive layers can bedisposed within the wells in any arrangement and/or configuration. Forexample, the organic light-emissive layers disposed in confinement wells920, 930, 940 are arranged having an alternating arrangement within eachrow. Adjacent rows can have the same arrangement or differingarrangement. In addition, while the adjacent rows of confinement wells920, 930, 940 are illustrated as having a uniform alignment, adjacentrows of confinement wells 920, 930, 940 can alternatively have anon-uniform alignment such as an offset arrangement. Moreover,confinement wells 920 and 930 can be reversed in the alternativepattern.

The configuration of each well 920, 930, 940 can have a rectangularshape such that each well is elongated in a vertical direction. Wells920, 930, 940 can have approximately the same dimensions in theelongated vertical direction. In addition, wells 920, 930, 940 can haveapproximately the same width. However, the entire well 940 associatedwith a blue organic light-emissive layer can correlate to a singlesub-pixel and thus pixel, while wells 920, 930 associated with the redand green organic light-emissive layer can correlate to a plurality ofsub-pixels and thus a plurality of pixels. For example, confinementwells 920, 930 can include a plurality of electrodes such that eachelectrode is associated with a differing sub-pixel of a differing pixel.As illustrated in FIG. 14, well 920 includes two electrodes 926, 928 andis associated with two differing pixels 950, 951.

A differing number of electrodes 926, 928, 936, 938, 946 can be disposedwithin differing confinement wells. For example, some confinement wells920, 930 can include a plurality of electrodes 926, 928; and 936, 938 soas to selectively address electrodes disposed in the same confinementwell but produce light emission for differing sub-pixels in differingpixels, while other confinement wells 940 only include one electrode 946to address an electrode disposed in one confinement well associated withone pixel. Alternatively, the number of electrodes disposed inconfinement well 940 can be half of the number of electrodes disposed inother confinement wells 920, 930. In addition, electrodes withindiffering confinement wells can have differing surface areas. Forexample, electrodes associated with light-emission within the bluewavelength range can have a greater surface area than electrodesassociated with light-emission within the red and/or green wavelengthrange to improve the life of display 900 and reduce power consumption.

Pixels 950, 951 can be defined based on the confinement well arrangementand corresponding sub-pixel layout. The overall spacing, or pitch, ofpixels 950, 951 can be based on the resolution of the display. Forexample, the higher the display resolution, the smaller the pitch. Inaddition, adjacent pixels can have differing pixel arrangements. Forexample, as illustrated in FIG. 14, pixel 950 can include a greensub-pixel G on the left, a blue sub-pixel B in the middle, and a redsub-pixel R on the right. Pixel 951 can include a red sub-pixel R on theleft, a blue sub-pixel B in the middle and a green sub-pixel G on theright.

FIG. 15 depicts a partial plan view of an exemplary embodiment of apixel and sub-pixel layout for an OLED display 1000. Features common toembodiments discussed above are not described (though similar labels canbe found with a 1000 series in FIG. 15). For simplicity, differenceswill be discussed. Confinement structure 1004 can be configured todefine a plurality of wells 1020, 1030, 1040. Wells 1020, 1030, 1040 canbe arranged such that wells 1020, 1030, 1040 are aligned in uniform rowswhere wells associated with red light emission and green light emission(for example 1020, 1030) alternate within a single row and wellsassociated with blue light emission (for example 1040) are within asingle row. In addition, wells 1020, 1030, 1040 can be configured suchthat the wells 1020, 1030, 1040 are aligned within a uniform column suchthat columns of wells 1020, 1040 alternate with columns of wells 1030,1040. Confinement wells 1020 and 1030 can be alternatively arranged suchthat confinement wells 1030 begin the alternating pattern.

Each confinement well 1020, 1030, 1040 can be approximately the samesize. However, the number of electrodes associated with each well 1020,1030, 1040 can differ. For example, as illustrated in FIG. 15, the wellassociated with red light emission 1020 can include electrodes 1026,1027, 1028, 1029, the well associated with green light emission 1030 caninclude electrodes 1036, 1037, 1038, 1039, and the well associated withblue light emission 1040 can include electrodes 1046, 1048. Whileelectrodes within confinement well 1040 are illustrated as beingarranged horizontally spaced, the electrodes could alternatively bearranged so as to be vertically spaced.

While electrodes 1026, 1027, 1028, 1029, 1036, 1037, 1038, 1039 areillustrated in FIG. 15 as having a square shape and electrodes 1046,1048 are illustrated as having a rectangular shape, electrodes havingany shape are contemplated as within the scope of the present disclosuresuch as, for example, circular, chevrons, hexagonal, asymmetrical,irregular curvature, etc. A plurality of differing shapes of electrodescould be implemented within a single confinement well. In addition,differing confinement wells can have differing shaped electrodes. Thesize and shape of the electrode can influence the distance between theelectrodes and thus the overall layout of the display. For example, whenthe shapes are complementary, electrodes can be spaced closer togetherwhile still maintaining electrical isolation between adjacentelectrodes. In addition, the shape and spacing of the electrodes caninfluence the degree of visual artifacts created. Electrode shapes canbe selected to reduce undesired visual artifacts and enhance imageblending to produce a continuous image.

Pixels 1050, 1051, shown in dashed lines, can be defined based on basedon the confinement well arrangement and corresponding sub-pixel layout.The overall spacing, or pitch, of pixels 1050, 1051 can be based on theresolution of the display. For example, the higher the displayresolution, the smaller the pitch. In addition, pixels can be defined ashaving an asymmetrical shape. For example, as illustrated in FIG. 15,pixel 1050, 1051 can have an “L” shape.

FIG. 16 depicts a partial plan view of an exemplary embodiment of apixel and sub-pixel layout for an OLED display 1100. Features common toexemplary embodiments discussed above will not be described (thoughsimilar labels with an 1100 series can be found in FIG. 16). Confinementstructure 1104 can be configured to define a plurality of confinementwells 1120, 1130, 1140 in a plurality of columns C₁, C₂, C₃, C₄. ColumnsC₁, C₂, C₃, C₄, can be arranged to produce a staggered arrangement. Forexample, the confinement wells in columns C₁, and C₃ can be offset fromcolumns C₂ and C₄, producing a staggered row arrangement whilemaintaining a uniform column arrangement. Pixels 1150, 1151 can bedefined based on the pitch of the confinement well arrangement. Thepitch of the confinement well arrangement can be based on the resolutionof the display. For example, the smaller the pitch the higher thedisplay resolution. In addition, pixels can be defined as having anasymmetrical shape. For example, as illustrated in FIG. 16 by the dashedlines, pixel 1150, 1151 can have a non-uniform shape.

FIG. 17 depicts a partial plan view of an exemplary embodiment of apixel and sub-pixel layout for an OLED display 1200. Features common toembodiments discussed above are not described (though similar labelswith a 1200 series can be found in FIG. 17). As illustrated in FIG. 17,confinement structure 1204 can be configured to define a plurality ofconfinement wells 1220, 1230, 1240. Each confinement well 1220, 1230,1240 can have a differing area. For example, the well 1220 associatedwith red light emission R can have an area greater than the well 1230associated with the green light emission G. In addition, confinementwells 1220, 1230, 1240 can be associated with a differing number ofpixels. For example, confinement well 1220 can be associated with pixels1251, 1252, 1254, 1256 and confinement wells 1230, 1240 can beassociated with pixels 1251, 1252. Wells 1220, 1230, 1240 can beconfigured in uniform rows R₁, R₂, R₃, R₄, R₅. Rows R₂, R₃, and R₅ canbe associated with blue light emission wells 1240 and rows R₁ and R₄ canbe associated with alternating red light emission wells 1220 and greenlight emission wells 1230. The confinement structure 1204 can have avariety of dimensions D₁, D₂, D₃, D₄. For example, D₁ can be greaterthan D₂, D₃, or D₄, D₂ can be less than D₁, D₃, or D₄, and D₃ can beapproximately equal to D₄.

FIG. 18 depicts a partial plan view of an exemplary embodiment of apixel and sub-pixel layout for an OLED display 1300. Features common toembodiments discussed above, for example FIG. 17, are not described(though similar labels with a 1300 series can be found in FIG. 18).Confinement structure 1304 can be configured to define a plurality ofconfinement wells 1320, 1330, 1340. Wells 1320, 1330, 1340 can bearranged such that wells associated with red light emission 1320 andgreen light emission 1330 can be alternated within a row with wellsassociated with blue light emission 1340.

While various pixel and sub-pixel layouts are described above, theexemplary embodiments in no way limit the shape, arrangement, and/orconfiguration of confinement wells that span a plurality of pixels asdescribed. Instead, confinement wells associated with the presentdisclosure in combination with inkjet printing manufacturing methodsallow for flexible pixel layout arrangements to be selected.

Various pixel layouts are contemplated that can enable a high resolutionOLED display using inkjet printing. For example, as illustrated in FIG.19, confinement structures 1404 can create a hexagonal pattern such thata pixel 1450 can comprise a confinement well 1420 associated with redemission R, a confinement well 1430 associated with green emission G,and a confinement well 1440 associated with blue emission B. Due to thepitch, the shape of the confinement wells, and the ability to pack theconfinement wells closer together, an OLED display having highresolution can be created using inkjet printing.

Embodiments disclosed herein can be used to achieve high resolution inany OLED display. Accordingly, it can be applied to various electronicdisplay apparatuses. Some non-limiting examples of such electronicdisplay apparatuses include television displays, video cameras, digitalcameras, head mounted displays, car navigation systems, audio systemsincluding a display, laptop personal computers, digital game equipment,portable information terminals (such as a tablet, a mobile computer, amobile telephone, mobile game equipment or an electronic book), imageplayback devices provided with recording medium. Exemplary embodimentsof two types of electronic display apparatuses are illustrated in FIGS.20 and 21.

FIG. 20 illustrates a television monitor and/or a monitor of a desktoppersonal computer that incorporates any of the OLED displays accordingto the present disclosure. Monitor 1500 can include a frame 1502, asupport 1504, and a display portion 1506. The OLED display embodimentsdisclosed herein can be used as the display portion 1506. Monitor 1500can be any size display, for example up to 55″ and beyond.

FIG. 21 illustrates an exemplary embodiment of a mobile device 1600(such as a cellular phone, tablet, personal data assistant, etc.) thatincorporates any of the OLED displays according to the presentdisclosure. Mobile device 1600 can include a main body 1062, a displayportion 1604, and operation switches 1606. The OLED display embodimentsdisclosed herein can be used as the display portion 1604.

Using various aspects in accordance with exemplary embodiments of thepresent disclosure, some exemplary dimensions and parameters could beuseful in attaining high resolution OLED displays with an increased fillfactor. Tables 1-3 include conventional dimensions and parameters aswell as prophetic, non-limiting examples in accordance with exemplaryembodiments of the present disclosure associated with an OLED displayhaving a resolution of 326 ppi where Table 1 describes a sub-pixelassociated with red light-emission, Table 2 describes a sub-pixelassociated with green light-emission, and Table 3 describes a sub-pixelassociated with blue light-emission. Tables 4-6 include conventionaldimensions and parameters as well as prophetic, non-limiting examples inaccordance with exemplary embodiments of the present disclosureassociated with a display having a resolution of 440 ppi where Table 4describes a sub-pixel associated with red light-emission, Table 5describes a sub-pixel associated with green light-emission, and Table 6describes a sub-pixel associated with blue light emission.

TABLE 1 For a sub-pixel associated with Length of Width of Area of redemission in display having Sub-pixel Sub-pixel Confinement resolution of326 ppi (μm) (μm) Well (μm²) Conventional sub-pixel 65.9 10.5 690.7Sub-pixel associated with 31.5 31.5 989.5 Confinement Structure asillustrated in FIGS. 3A, 3B Conventional sub-pixel with 59.9 9.0 537.9Pixel Definition Layer Sub-pixel associated with 28.5 28.5 809.8Confinement Structure with definition layer as illustrated in FIGS. 5A,5B

TABLE 2 For a sub-pixel associated with Length of Width of Area of greenemission in display having Sub-pixel Sub-pixel Confinement resolution of326 ppi (μm) (μm) Well (μm²) Conventional sub-pixel 65.9 10.5 690.7Sub-pixel associated with 31.5 31.5 989.5 Confinement Structure asillustrated in FIGS. 3A, 3B Conventional sub-pixel with 59.9 9.0 537.9Pixel Definition Layer Sub-pixel associated with 28.5 28.5 809.8Confinement Structure with definition layer as illustrated in FIGS. 5A,5B

TABLE 3 For a sub-pixel associated with Length of Width of Area of blueemission of a display Sub-pixel Sub-pixel Confinement having resolutionof 326 ppi (μm) (μm) Well (μm²) Conventional sub-pixel 65.9 21.0 1381.4Sub-pixel associated with 30.0 65.9 1979.1 Confinement Structure asillustrated in FIGS. 3A, 3B Conventional sub-pixel with 59.9 18.0 1075.9Pixel Definition Layer Sub-pixel associated with 27.0 59.9 1619.6Confinement Structure with definition layer as illustrated in FIGS. 5A,5B

TABLE 4 For a sub-pixel associated with Length of Width of Area of redemission of a display Sub-pixel Sub-pixel Confinement having resolutionof 440 ppi (μm) (μm) Well (μm²) Conventional sub-pixel 45.7 5.4 248.4Sub-pixel associated with 21.4 21.4 456.4 Confinement Structure asillustrated in FIGS. 3A, 3B Conventional sub-pixel with 39.7 3.9 159.2Pixel Definition Layer Sub-pixel associated with 18.4 18.4 337.2Confinement Structure with definition layer as illustrated in FIGS. 5A,5B

TABLE 5 For a sub-pixel associated with Length of Width of Area of greenemission of a display Sub-pixel Sub-pixel Confinement having resolutionof 440 ppi (μm) (μm) Well (μm²) Conventional sub-pixel 45.7 5.4 248.4Sub-pixel associated with 21.4 21.4 456.4 Confinement Structure asillustrated in FIGS. 3A, 3B Conventional sub-pixel with 39.7 3.9 156.2Pixel Definition Layer Sub-pixel associated with 18.4 18.4 337.2Confinement Structure with definition layer as illustrated in FIGS. 5A,5B

TABLE 6 For a sub-pixel associated with Length of Width of Area of blueemission of a display Sub-pixel Sub-pixel Confinement having resolutionof 440 ppi (μm) (μm) Well (μm²) Conventional sub-pixel 45.7 10.9 496.8Sub-pixel associated with 20.0 45.7 912.8 Confinement Structure asillustrated in FIGS. 3A, 3B Conventional sub-pixel with 39.7 7.9 312.4Pixel Definition Layer Sub-pixel associated with 17.0 39.7 674.4Confinement Structure with definition layer as illustrated in FIGS. 5A,5B

Table 7 includes conventional dimensions and parameters as well asprophetic, non-limiting examples in accordance with exemplaryembodiments of the present disclosure associated with a pixel within adisplay having a resolution of 326 ppi where the pixel includes a redsub-pixel, a green sub-pixel, and a green sub-pixel.

TABLE 7 For a display having Active Area of Total Area of Fillresolution of 326 PO Pixel (μm²) Pixel (μm) Factor* ConventionalConfinement 2762.7 6070.6 46% Structure Confinement Structure as 3958.26070.6 65% illustrated in FIGS. 3A, 3B Conventional Confinement 2151.86070.6 35% Structure with Pixel Definition Layer Confinement Structurewith 3239.2 6070.6 53% definition layer as illustrated in FIGS. 5A, 5B*(Active Area/Total Area) rounded up to the nearest percentage point

As illustrated in Table 7 above, it is contemplated that variousexemplary embodiments in accordance with the present disclosure canachieve a fill factor improvement over conventional confinementstructures. For example, a fill factor for a display that contemplates aconfinement structure illustrated in FIGS. 3A and 3B can increase thefill factor by about 43% over a conventional structure, therebyachieving a total fill factor of 65%. In another embodiment, a fillfactor for a display that contemplates a confinement structure asillustrated in FIGS. 5A and 5B can improve the fill factor by about 51%over a conventional structure thereby achieving a total fill factor of53%.

Table 8 includes conventional dimensions and parameters as well asprophetic, non-limiting examples in accordance with exemplaryembodiments of the present disclosure associated with a pixel within adisplay having a resolution of 440 ppi where the pixel includes a redsub-pixel, a green sub-pixel, and a green sub-pixel.

TABLE 8 For a display having Active Area of Total Area of Fillresolution of 440 PO Pixel (μm²) Pixel (μm) Factor* ConventionalConfinement 993.5 3332.4 30% Structure Confinement Structure as 1825.63332.4 55% illustrated in FIGS. 3A, 3B Conventional Confinement 624.83332.4 19% Structure with Pixel Definition Layer Confinement Structurewith 1348.9 3332.4 40% definition layer as illustrated in FIGS. 5A, 5B*(Active Area/Total Area) rounded up to the nearest percentage point

As illustrated in Table 8 above, it is contemplated that variousexemplary embodiments in accordance with the present disclosure canachieve a fill factor improvement over conventional confinementstructures. For example, a fill factor for a display that contemplates aconfinement structure illustrated in FIGS. 3A and 3B can improve thefill factor by about 84% over conventional structure thereby achieving atotal fill factor of 55%. In another embodiment, a fill factor for adisplay that contemplates a confinement structure as illustrated inFIGS. 5A and 5B can improve the fill factor by about 116% over aconventional structure thereby achieving a total fill factor of 40%.

Various exemplary embodiments described above and pursuant to thepresent disclosure can permit inkjet printing of OLED displays havingrelatively high pixel density and increased fill factors by increasingthe size of the confinement wells into which the OLED material dropletsare loaded and thereby enable the use of attainable droplet sizes andattainable inkjet system droplet placement accuracies, according to thepresent disclosure. Due to the larger confinement well areas, highresolution OLED displays can be manufactured using sufficiently largeinkjet droplet volumes and attainable droplet placement accuracies,without needing to utilize too small of droplet volumes or excessivelyhigh droplet placement accuracies that could pose prohibitive challengesin inkjet equipment design and printing techniques. Without implementinga confinement well that spans a plurality of sub-pixels according to thepresent disclosure, droplet size and system droplet placement errorscould significantly increase issues in any high resolution displaymanufactured using existing inkjet heads, as the droplets would have toolarge volumes and would overfill each sub-pixel well and theconventional droplet placement accuracies would lead to misplacement ofdroplets either entirely or partially outside of the target confinementwell, both of which would lead to undesired errors in film depositionand corresponding visual defects in the final display appearance. Theability to achieve high pixel density with existing droplet volumes anddroplet placement accuracies enables the techniques described herein tobe utilized in the manufacture of displays of relatively highresolutions for many applications, from small size displays, such as,for example, are found in smart phones and/or tablets, and large sizedisplays, such as, for example, ultra high resolution televisions.Moreover, achieving OLED material layer(s) of substantially uniformthickness that sufficiently conform to underlying topography, inaccordance with exemplary embodiments, can promote overall OLED displayperformance and quality, and in particular can permit desirableperformance and quality to be achieved in high resolution OLED displays.One or more of the above described embodiments can achieve a reducedfill factor. In conventional pixel arrangements, a fill factor for adisplay having a resolution in the range of 300-440 ppi has a fillfactor of less than 40%, and frequently less than 30%. In contrast,exemplary embodiments of the present disclosure may achieve a fillfactor of greater than 40%, and in some instances as high as 60%, fordisplays having a resolution in the range of 300-440 ppi. The exemplaryembodiments can be used for any pixel size and arrangement, includingpixel arrangements within high resolution displays.

The exemplary embodiments can be used with any size display and moreparticularly with small displays having a high resolution. For example,exemplary embodiments of the present disclosure can be used withdisplays having a diagonal size in the range of 3-70 inches and having aresolution greater than 100 ppi, for example, greater than 300 ppi.

Although various exemplary embodiments described contemplate utilizinginkjet printing techniques, the various pixel and sub-pixel layoutsdescribed herein and the way of producing those layouts for an OLEDdisplay can also be manufactured using other manufacturing techniquessuch as thermal evaporation, organic vapor phase deposition, organicvapor jet printing. In exemplary embodiments, alternative organic layerpatterning can also be performed. For example, patterning methods caninclude shadow masking (in conjunction with thermal evaporation) andorganic vapor jet printing. In particular, though the pixel layoutsdescribed herein, in which multiple sub-pixels of the same color aregrouped together and in which the deposited OLED film layers spansubstantial topographies within the grouped sub-pixel regions, have beenconceived for inkjet printing applications, such layouts can also havebeneficial alternative application to vacuum thermal evaporationtechniques for OLED film layer deposition, in which the patterning stepis achieved using shadow masking. Such layouts as described hereinprovide for larger shadow mask holes and increased distances betweensuch holes, thereby potentially improving the overall mechanicalstability and general practicality of such shadow masks. While vacuumthermal evaporation techniques with shadow masks may be not as low costas inkjet techniques, the use of the pixel layouts in accordance withthe present disclosure and the use of OLED film layer coatings spanningsubstantial topographies within the grouped sub-pixels associated withthe same color, also represent a potentially important application ofthe present disclosure described herein.

Although only a few exemplary embodiments have been described in detailabove, those skilled in the art will readily appreciate that manymodifications are possible in the example embodiments without materiallydeparting from this disclosure. Accordingly, all such modifications areintended to be included within the scope of this disclosure as definedin the following claims.

It is to be understood that the various embodiments shown and describedherein are to be taken as exemplary. Elements and materials, andarrangement of those elements and materials, may be substituted forthose illustrated and described herein, and portions may be reversed,all as would be apparent to one skilled in the art after having thebenefit of the description herein. Changes may be made in the elementsdescribed herein without departing from the spirit and scope of thepresent disclosure and following claims, including their equivalents.

Those having ordinary skill in the art will recognize that variousmodifications may be made to the configuration and methodology of theexemplary embodiments disclosed herein without departing from the scopeof the present teachings.

Those having ordinary skill in the art also will appreciate that variousfeatures disclosed with respect to one exemplary embodiment herein maybe used in combination with other exemplary embodiments with appropriatemodifications, even if such combinations are not explicitly disclosedherein.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the devices, methods, andsystems of the present disclosure without departing from the scope ofthe present disclosure and appended claims. Other embodiments of thedisclosure will be apparent to those skilled in the art fromconsideration of the specification and practice of the disclosuredisclosed herein. It is intended that the specification and examples beconsidered as exemplary only.

What is claimed is:
 1. An organic light-emitting diode display,comprising: a confinement structure provided on a substrate, theconfinement structure defining a plurality of wells; a plurality ofelectrodes disposed within the plurality of wells; a first organiclight-emissive layer having a first light-emissive wavelength disposedwithin each of a plurality of first wells of the plurality of wells; asecond organic light-emissive layer having a second light-emissivewavelength disposed within each of a plurality of second wells of theplurality of wells; and a third organic light-emissive layer having athird light-emissive wavelength disposed within each of a plurality ofthird wells of the plurality of wells, wherein a number of electrodesdisposed within each of the plurality of first and second wells differsfrom a number of electrodes disposed within each of the plurality ofthird wells.
 2. The organic light-emitting diode display of claim 1,wherein the first light-emissive wavelength is associated with red lightemission, the second light-emissive wavelength is associated with greenlight emission, and the third light-emissive wavelength is associatedwith blue light emission.
 3. The organic light-emitting diode display ofclaim 1, wherein pixels of the organic light-emitting diode display aredefined by a group of electrodes and corresponding light-emissive layersfrom each of one of the plurality of first wells, one of the pluralityof second wells, and one of the plurality of third wells.
 4. The organiclight-emitting diode display of claim 1, wherein at least the pluralityof first wells and the second wells each contain a plurality ofelectrodes, each of the plurality of electrodes disposed within theplurality of first wells and the second wells being associated withdiffering pixels of the organic light-emitting diode display.
 5. Theorganic light-emitting diode display of claim 1, wherein each of theplurality of electrodes disposed within the plurality of first wells andthe plurality of second wells has an active region having a first area,and each of the plurality of electrodes disposed within the plurality ofthird wells has an active region having a second area, the second areabeing greater than the first area.
 6. The organic light-emitting diodedisplay of claim 1, wherein: the first light-emissive wavelength isassociated with red light emission, the second light-emissive wavelengthis associated with green light emission, the third light-emissivewavelength is associated with blue light emission, and each electrode ofthe plurality of electrodes disposed within a well is associated with arespective subpixel corresponding to one of the red light emission,green light emission, or blue light emission.
 7. The organiclight-emitting diode display of claim 6, wherein: the plurality of wellsare arranged in alternating first and second rows, the first row havingthe plurality of first wells and second wells alternatingly disposed,and the second row having the plurality of third wells consecutivelydisposed.
 8. The organic light-emitting diode display of claim 7,wherein the plurality of third wells are staggered relative to theplurality of first and second wells.
 9. The organic light-emitting diodedisplay of claim 7, wherein: the plurality of wells of each row of thefirst and second rows are aligned so as to form columns of wells, thecolumns of wells being arranged in alternating first and second columns,the first column having the plurality of first and third wellsalternatingly disposed, and the second column having the plurality ofsecond and third wells alternatingly disposed.
 10. The organiclight-emitting diode display of claim 9, wherein the plurality of wellsin each row of the first and second rows are aligned in columns suchthat each column contains one of the plurality of first wells, thesecond wells, or the third wells.
 11. The organic light-emitting diodedisplay of claim 1, wherein: the plurality of wells are arranged inalternating first and second columns, the first column comprising of theplurality of first wells and third wells alternatingly disposed, and thesecond column comprising of the plurality of second wells and thirdwells alternatingly disposed.
 12. The organic light-emitting diodedisplay of claim 11, wherein the plurality of wells of the first columnand the plurality of wells of the second column are in a staggeredarrangement relative to each other.
 13. The organic light-emitting diodedisplay of claim 1, wherein the plurality of wells are arranged in rows,each row comprising of plurality of first, second, and third wellsdisposed in series.
 14. The organic light-emitting diode display ofclaim 1, wherein: a number of electrodes disposed in each of theplurality of third wells is half of a number of electrodes disposed ineach of the plurality of first wells and the second wells.
 15. Theorganic light-emitting diode display of claim 1, wherein a plurality ofelectrodes separated from each other are disposed in each of at leastthe plurality of first and second wells.
 16. The organic light-emittingdiode display of claim 1, wherein each of the first organiclight-emissive layer, the second organic light-emissive layer, and thethird organic light-emissive layer is a substantially continuous layerthat spans and is contained within each well of the plurality of wells,and has a surface facing away from the substrate with a non-planartopography.
 17. An organic light-emitting diode display, comprising: aconfinement structure provided on a substrate, the confinement structuredefining a plurality of wells, the plurality of wells including a firstwell, a second well, and a third well; a first plurality of electrodesdisposed in the first well, wherein each electrode in the first well isassociated with a differing pixel of the organic light-emitting diodedisplay; a second plurality of electrodes disposed in the second well,wherein each electrode in the second well is associated with a differingpixel of the organic light-emitting diode display; a third plurality ofelectrodes disposed within the third well; a first organiclight-emissive layer having a first light-emissive wavelength disposedin the first well; a second organic light-emissive layer having a secondlight-emissive wavelength disposed in the second well; and a thirdorganic light-emissive layer having a third light-emissive wavelengthdisposed in the third well, wherein each of the first plurality ofelectrodes and the second plurality of electrodes disposed within thefirst well and the second well has an active region having a first area,and each of the third plurality of electrodes disposed within the thirdwell has an active region having a second area, the second area beinggreater than the first area.
 18. The organic light-emitting diodedisplay of claim 17, wherein a number of electrodes disposed in each ofthe first and second wells differs from a number of electrodes disposedin the third well.
 19. The organic light-emitting diode display of claim17, wherein the third plurality of electrodes are disposed in the thirdwell and each electrode of the third plurality of electrodes in thethird well is associated with a differing pixel of the organiclight-emitting diode display.
 20. The organic light-emitting diodedisplay of claim 17, wherein the number of electrodes disposed in thethird well is half of the number of electrodes disposed in the firstwell or the second well.
 21. The organic light-emitting diode display ofclaim 17, wherein pixels of the organic light-emitting diode displayhave an asymmetrical shape.
 22. The organic light-emitting diode displayof claim 17, wherein the first light-emissive wavelength is associatedwith red light emission, the second light-emissive wavelength isassociated with green light emission, and the third light-emissivewavelength is associated with blue light emission.
 23. The organiclight-emitting diode display of claim 17, wherein pixels of the organiclight-emitting diode display are defined by a group of electrodes andcorresponding light-emissive layers from each of one of the first wells,one of the second wells, and one of the third wells.